Post on 19-Aug-2020
Improving Energy Efficiency in
Historic Cornish Buildings Cornwall Council Historic Environment Service
Camborne, Roskear, Tuckingmill Townscape Heritage Initiatives
Acknowledgements
This report was written by:
Andrew Richards, Advice Team Leader (West), Cornwall Council
And produced with assistance from
Peter Smith, THI Administrative Officer, Cornwall Council
This followed preparatory work from Will Segal and Marc Staddon, students from Cornwall College’s FdSc Renewable Energy
Technologies Course.
Iain McCaig Building Conservation and Research Team
English Heritage
Dr Michael Hunt Curriculum Area Manager for Science,
Cornwall College
Claire Lenihan Lecturer - Technology Faculty, Cornwall College
Adele Oakes Business and Enterprise Faculty Site Access
Coordinator, Cornwall College
Kay Pearce Cornwall College Student
Phil Brown Cornish Lime Company
Paul Watts Mike Wye and Associates Ltd
Antony Best Eddie Jewell Acoustics
Paul Bright Chief Exec, Cornwall Sustainable Buildings Trust
Sarah Williams Building Control, Cornwall Council
Caius Simmons THI Project Manager, Cornwall Council
Dr Alyson Cooper Principal HE Officer, Cornwall Council
Dan Nicholls Natural Resources, Planning and Regeneration,
Cornwall Council
Contributions were also received from:
Planning Status
This ‘Improving Energy Efficiency in Historic Cornish Buildings’
guide was approved by Cornwall Council as a material consideration for land use planning purposes in June 2014.
Limitations of this guidance
This guide includes costs and references to products, suppliers, contractors and organisations. It includes web links highlighted in
blue to enable further research. This information is believed to be accurate at the time of issue. It is liable to change, however, and every effort will be made to review and update it. The references
to products, suppliers and contractors is not comprehensive and there may be other suitable products and firms not included in
the guide. Any inclusion of products and firms does not constitute a recommendation as to their suitability.
Costs
Unless otherwise indicated, costs in this document have been
provided by: EC Harris Built Asset Consultancy, Exeter. www.echarris.com. All capital costs provided are based on prices
at 2nd Quarter 2016. These capital costs are forecast to increase 4% year on year until 2nd Quarter 2019 (i.e. prices included will require uplifting by 12% in 2nd Quarter 2019)
Further information
If you have any queries on the products, firms or suppliers highlighted in this guide please contact:
andrew.richards@cornwall.gov.uk
Executive Summary
Sections within the guide provide information and advice on:
Why historic buildings are worth keeping and policybackground for retrofitting (Section 1).
The influence of climate and climate change on historicCornish buildings and factors affecting energy reduction.(Section 2).
How historic buildings work, ways of controlling moistureand maintaining healthy living conditions (Section 3).
Simple changes in occupants’ behaviour that can reduceenergy consumption (Section 4).
Suitable products for retrofitting historic buildings andgood local examples of their use including performancedetails and costs. Useful web links are provided within
sections of the guide to enable further research and will beregularly updated (Section 5).
Details of sustainable materials that could be used forextensions to historic buildings or new buildings withinhistoric areas. (Section 6).
Reclaimed and recyclable materials (Section 7).
Available funding and useful contacts (Sections 8 and 9).
Feedback on energy monitoring carried out throughCamborne, Roskear, Tuckingmill THIs (Appendix 1).
Energy saving options for heating, lighting and appliances(Appendix 2).
Microgeneration options and guidance (Appendix 3).
Local case studies (Appendix 4).
Historic buildings all differ and are subject to varying levels of
protection under the planning system. They vary in their construction, location, quality of services and the way they are
used. Consequently there is no ‘one size fits all’ solution to upgrade their energy efficiency.
Retrofitting can often damage the authenticity, character and setting of a historic building. This guide highlights behavioural
changes and principles that could be followed to upgrade a historic building whilst retaining its special character.
The guide provides local examples of good practice along with current costs and performance details of suitable products. It is
intended to be used by local authority staff, building owners, professional agents and contractors at an early stage in the
planning process and before Building Control applications.
THI funded energy saving measures in converted historic buildings at the former Holman’s No.3 Engineering Works,
Trevu Road, Camborne.
1. General information 1
1.1 Introduction 2
1.2 Why historic buildings are worth keeping 3
1.3 The National Planning Policy Framework 3
1.4 Historic buildings 3
1.5 Listed Building Consent 4
1.6 Principles of repair and alteration 5
1.7 Building Regulations and historic buildings 6
1.8 Energy Performance Certificates 7
1.9 BREEAM 7
1.10 Measurement terms explained 8
2. The impact of climate change on Cornish 9
historic buildings
2.1 Cornish climate and historic buildings 10
2.2 Embodied energy 11
2.3 Thermal mass 11
2.4 Heat loss 12
2.5 Reducing energy use and carbon emissions 13-14
in traditional buildings
3. Keeping buildings healthy and comfortable 15
3.1 Why solid walled buildings need to breathe 16
3.2 Internal moisture vapour 16
3.3 Condensation and dew points 17
3.4 Membranes and barriers 17
3.5 Healthy buildings 17
3.6 Ways of controlling moisture 18
3.7 Ventilation and security 19
3.8 Trickle ventilation 20
4. Reducing energy consumption 21
4.1 Introduction 22
4.2 ‘Trigger Points’ for retrofitting 22
4.3 Reasons to retrofit 22
4.4 Simple ways to reduce energy use 23
4.5 Heating systems 24
4.6 Draught reduction 25
5. Building fabric improvements 26
5.1 Introduction 27
5.2 Windows 27
5.2.1 Improving the performance of traditional 27
windows
5.2.2 Repairs and maintenance 28-29
5.2.3 Draught proofing 30-31
5.2.4 Secondary glazing 32-33
5.2.5 Shutters 34-35
5.2.6 Thermal blinds and thermal curtains 36
5.2.7 Double glazing 37-38
5.2.8 Types of glass 39
5.3 Insulation 40-41
5.4 Roof insulation 42
5.5 Floor insulation 43-44
5.6 Wall insulation 45
5.6.1 External wall insulation 46-47
5.6.2 Internal wall insulation 48-53
5.6.3 Cavity/hollow wall insulation 54
5.7 Costings and performance tables 55-56
5.8 Links to guidance on insulation 57
5.9 Further technical guidance 57
5.10 Suppliers and products 58
6. Sustainable materials 59
6.1 Sustainability 60
6.2 Building materials 60
6.2.1 Timber 61
6.2.2 Hempcrete 62
6.2.3 Straw bale construction 62
6.2.4 Cob 63
6.2.5 Thermoplan clay block system 64
6.2.6 Rammed earth 65
6.2.7 Green roofs 65
6.2.8 Sustainable finishes 66
6.2.9 Painting traditional joinery 67
6.2.10 Sustainable finishes suppliers 68
6.2.11 Sustainable building materials 69
Page Page Contents
7. Reclaimed and recyclable materials 70
7.1 Architectural salvage 71
7.2 Minimising waste 71
7.3 Metal rainwater goods 71
8. Funding options 72
8.1 Current funding schemes 73
8.2 Tax savings 74
8.3 Additional income 74
9. Further information and advice 75
9.1 Organisations 76-77
9.2 Professional services 77
9.3 Local contractors for historic building work 78
Page
Appendix 1: Energy efficiency and noise monitoring
Appendix 2: Energy saving guidance / cost comparisons on heating, lighting
and appliances
Appendix 3: Microgeneration
Appendix 4: Case studies
Contents
Appendices
THI grant funded internal shutters (first floor) and secondary
glazing (ground floor) to traditional single glazed sash windows, Trevu Road, Camborne.
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1. General information
Main contents
1.1 Introduction
The Heritage Lottery Fund’s Townscape Heritage Initiative (THI) programme funds traditional repairs to targeted historic buildings in
Conservation Areas. The Camborne, Roskear, Tuckingmill THIs (2008-2016) are multi funded grant schemes administered by staff
from Cornwall Council’s Historic Environment Service and have an emphasis on traditional skills training and energy saving measures.
This guide has been written and produced by Andrew Richards and Peter Smith of the THI Project Team and complements the
energy saving initiatives progressed through the schemes. Further details of the THIs including slide shows of completed works and
summaries of ongoing traditional skills training and energy saving initiatives are accessible via links on the THI web page:
Camborne, Roskear, Tuckingmill Townscape Heritage Initiatives
Details of other heritage led regeneration schemes carried out by Cornwall Council’s Historic Environment Service are available
through the following link:
Cornwall Council - Heritage Led Regeneration
Cornwall College students assessing energy saving measures during redevelopment of the former Holman’s No.3 Engineering
Works, Trevu Road, Camborne
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1. General information
Main contents
1. General information
1.4 Historic buildings
3
Historic buildings are usually recognised as:
Listed buildings.
Buildings within Conservation Areas.
Buildings of local architectural or historical interest which are
referred to as a material consideration in a Local Authority’s
Development Plan.
Buildings of local architectural or historical interest withinnational parks, areas of outstanding natural beauty or World
Heritage Sites.
Scheduled monuments.
For information on listed buildings and to check if a building is
listed please use the following link:
Cornwall Council - Listed buildings
For information on Conservation Areas and to check if a building
is in a Conservation Area please use the following link:
Cornwall Council - Conservation Areas
Unlisted building in Helston Conservation Area renovated
through Helston THI
Grade I Listed C16 Gatehouse, Trenethick Barton, Helston.
1.2 Why historic buildings are worth
keeping Historic buildings are inherently sustainable. Most have survived because they are robust, durable and adaptable. Original materials
and architectural detailing often survive and can be easily repaired, maintained and recycled at the end of their service life.
They are part of our cultural heritage and reflect the nature and
history of the communities that created them. They add distinctiveness, meaning and quality to the places we live and provide a sense of continuity and identity. The following links
provide more details on the importance of historic buildings:
Historic England - Heritage and People: Value and Impact
IHBC - Valuing Historic Places
Heritage Counts - Historic Environment and Sense of Place
1.3 The National Planning Policy
Framework (NPPF) The NPPF sets out the Government’s planning policies for England and how these are expected to be applied. It stresses the need to
understand the reason why people value particular buildings or places, so that changes can be made to them without losing the
things that make them special. It refers to places which have cultural and economic value to society as heritage assets and defines them as:
“a building, monument, site, place, area or landscape positively
identified as having a degree of significance meriting consideration in planning decisions”
It defines significance as the value of a heritage asset to our own and future generations because of its heritage interest. In other
words significance is the sum of all cultural values people associate with a building or place.
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1. General information
1.5 Listed Building Consent
Listed Building Consent is needed for the alteration or extension of a listed building, which would affect its character in any way.
Carrying out unauthorised works on a listed building is a criminal offence. Consult Cornwall Council’s Planning and
Building Control services before making any changes:
Cornwall Council - Planning
Cornwall Council - Listed building information including FAQs
Cornwall Council - Planning and Listed Building application forms
Extension to Grade II Listed Nansloe Manor, Helston.
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1. General information
As the nature of historic fabric varies between buildings and within buildings it is important that a methodical approach is taken to
assess the impact of any proposed interventions. This approach should take the following principles into account:
Minimise disturbance of historic fabric.
Keep works to the minimum necessary.
Ensure any new works are reversible.
Take a holistic approach and fully understand the building.
Avoid impermeable materials or membranes in breathable traditional construction.
Be aware of the contribution that the manufacture or use of new materials make to greenhouse gases / carbon emissions.
Historic England’s Conservation Principles, Policy and Guidance 2008 provides a comprehensive framework for the sustainable manage-
ment of the historic environment.
1.6 Principles of repair and alteration
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Piggery converted to café, Godolphin House, Helston. Internally fixed glazing minimises intervention and retains character.
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‘Honest’ lift extension to Grade I Listed Godolphin House.
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1. General information
Buildings used primarily or solely as places of worship are exempt
from Part L altogether although this doesn't apply to other parts of the building used separately for offices, meetings, catering,
etc.
There is usually some flexibility in how the Regulations can be interpreted when upgrading historic buildings and a compromise solution can often be reached which retains the building’s
character. The aim when upgrading historic buildings should be to improve energy efficiency as far as reasonably practicable
without damaging their character or causing long term deterioration. Further information is available through the following links:
Historic England guidance on the Building Regulations
Historic England - Energy Efficiency and Historic Buildings -
Application of Part L of the Building Regulations to historic and traditionally constructed buildings
The Building Regulations are evolving regularly through government commitments under the Climate Change Act 2008.
Latest versions should always be used and are available through the following link:
Planning Portal - Building Regulations
To obtain advice and check whether a Building Control application is required, please contact Cornwall Council’s Building Control
Service through the following link:
Cornwall Council Building Control Service Information
Advice on appropriate and sympathetic ways of upgrading historic buildings can be obtained from your local Conservation Officer:
Cornwall Council - Building Conservation Contacts
1.7 Building Regulations and historic
buildings
The Building Regulations 2010 set standards for design and construction that apply to most new buildings and alterations to
many existing buildings, including Listed buildings. Any new work such as extensions and alterations will require Building Regulation
Approval. There is no general requirement, however, to upgrade all existing buildings to comply with Building Regulations.
In the Regulations, Part L: Energy Conservation deals with conservation of fuel and power and is most relevant in terms of
upgrading the performance of historic buildings.
Listed buildings, buildings within a Conservation Area or Scheduled Monuments are exempt from compliance with the energy efficiency requirements of this part if proposed works
would unacceptably alter the character, appearance and significance of a building.
Special consideration can also be given under Part L to the
following buildings: Buildings of architectural or historic interest listed in the
Local Development Plan (locally listed buildings).
Buildings of architectural or historic interest that are within National Parks, Areas of Outstanding Natural Beauty,
Registered Parks, Gardens and Battlefields, World Heritage Sites and the curtilage of Scheduled Ancient Monuments or World Heritage Sites.
Buildings of traditional construction with permeable fabric that
both absorbs and readily allows the evaporation of moisture (which can conflict with modern materials and methods).
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1. General information
1.8 Energy Performance Certificates
Energy Performance Certificates (EPCs) show a building’s
performance in bands similar to those used to indicate the efficiency of electrical appliances. They are now needed when
both residential and commercial properties are built, sold or rented. An EPC contains information about a property’s energy use, typical energy costs and recommendations about how to
reduce energy use and save money. They give an energy efficiency rating from ‘A’ (most efficient) to ‘G’ (least efficient)
and are valid for 10 years.
There are exemptions on officially protected buildings (e.g. Listed buildings), places of worship, temporary buildings, stand alone buildings with a total useful floor area of less than 50m² and
incomplete or due to be demolished buildings. Failure to comply with EPC legislation could result in fines of up to £5,000.
EPCs are carried out by qualified assessors, regulated by an approved accreditation scheme. It involves assessment of boilers, heating controls, insulation and windows.
Further information
Historic England - Energy Performance Certificates
Gov.uk - Energy Performance Certificates
Community Energy Plus - Energy Performance Certificates
Energy Saving Trust - Energy Performance Certificates
BREEAM is an environmental assessment method and rating system for buildings that was launched in 1990. It sets the standard for best practice in sustainable building design, construction and operation and provides a comprehensive measure of a building's environmental performance. It encourages low carbon, low impact design and minimising the energy demands created by a building before energy efficiency and low carbon technologies are considered.
For further information see the following link: BREEAM
1.9 Building Research Establishment
Environmental Assessment Method
(BREEAM)
7 Main contents
Sample EPC for THI funded Reynolds House (part of former
Holman’s No.3 Works, Trevu Road, Camborne) and BREEAM certificate for the converted Carpenter’s Shop, Heartlands, Pool.
1. General information
Performance data in this guide
Savings / Payback: where indicated these are Energy Savings
Trust (EST) estimates based on a hypothetical three bedroom gas heated semi-detached property. The figures are theoretical approximations - real savings and costs may differ considerably.
Costs: prices are estimates. Purchasing in bulk could help to
reduce costs. Each price is written in context of the thickness it comes in / is applied in. Unless otherwise indicated, costs have
been provided by E C Harris Built Asset Consultancy, Exeter and are based on building costs for medium-sized projects.
1.10 Measurement terms explained
K (or λ lambda) values: the ‘thermal conductivity’ values –
the standard unit of measurement for any material’s ability to
conduct heat. The higher the k-value of an insulation material the thicker the layer that will be required to achieve a desired
U- value. K values are usually given in manufacturers’ literature and are used to calculate U-values.
U-values: a measure of heat flow through a composite building
element such as a wall, floor or roof. The higher the U-value the worse the thermal performance of the element. A low U-value usually indicates high levels of insulation. They provide a way of
assessing the thermal performance of the building element and
are used to demonstrate compliance with Building Regulations.
R-values: an expression of thermal resistivity for a material of a
given thickness. The higher the R-value, the better the insulator.
SAP and RdSAP: The Government’s methodology for assessing and comparing energy and environmental performance is:
Standard Assessment Procedure (SAP) - new buildings
Reduced Data Sap (RdSAP) - existing dwellings
SAP ratings are expressed on a scale of 1 to 100. A higher number denotes a better rating. SAPs are accepted by Building
Control but RdSAPs are not as they are generic as opposed to property specific. Information on SAPs, EPCs and air pressure
tests is available through the ES Consult section of the Council’s website:
ESConsult - Extended Services
Further information on SAP and RdSAP assessments:
Gov.uk - Standard Assessment Procedure (SAP)
Building Research Establishment - SAP ratings
8 Main contents
Screenshot of Cornwall Council’s ESConsult web page.
2. The impact of climate change on historic Cornish buildings
9 Main contents
Bottom photo: Storm at Portreath (photo copyright S.Oram).
2.1 Cornish climate and historic buildings Cornwall is one of the UK’s more exposed areas with around 300
miles of coastline. MET Office data shows that only western Scotland has greater average wind speeds than the south west of England. Annual rainfall totals for most coastal areas of Cornwall and Devon
are 900-1000mm, but up to double this amount falls on upland areas such as Dartmoor, Bodmin Moor and Exmoor. These rainfall figures
can be compared to annual totals of around 500mm in the driest parts of Eastern England and over 4000mm in the western Scottish mountains.
The combination of a relatively high annual rainfall and exposure to
wind has influenced the style of buildings and the types of building materials used in the South West.
Cornish vernacular buildings were often robustly built of locally quarried stone and slate to withstand local weather conditions. Build-
ing stone included granite, elvan and killas, all of which have differing properties. Other common walling materials were hung slate, cob and
occasionally brick. Roofs were mostly in locally quarried Delabole and Trevillet slate although thatch is common in certain areas.
To withstand the local weather building techniques such as wet laid roofs and slate hanging to walls emerged to prevent up lift from wind
and protection from horizontal driving rain. Poorer quality building stone was often limewashed or lime rendered.
More information on Cornish building materials:
English Heritage county building stone atlases
More information on climate change affecting Cornwall:
Cornwall Council - Climate change and energy
Met Office - South West England: climate
Wikipedia - Geography of Cornwall
Historic England - Heritage and Climate Change
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2. The impact of climate change on historic Cornish buildings
Main contents
Heavy rain at Commercial Street, Camborne
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2. The impact of climate change on historic Cornish buildings
2.3 Thermal mass
Many solid walled historic buildings have good thermal mass. This is the ability of a material to absorb, store and release heat
over time. Older buildings can save energy costs by absorbing and storing heat from solar gains and internal appliances and releasing
it at a later stage. This will happen quicker with well insulated lightweight materials than dense masonry walls. Thermal mass can also help prevent overheating in the summer and reduce the need
for mechanical cooling.
2.2 Embodied energy
Upgrading historic buildings is a more sustainable option than pulling them down and building new structures. Embodied energy
is the energy used for the erection of a building. Operational energy is that used in the operation of a building. Both activities
result in emissions of carbon dioxide. Embodied energy includes the energy used to extract raw materials, the manufacture of
building products and construction on site as well as the energy used to transport the materials and products. Retaining an existing building instead of replacing it with a new one avoids the
embodied energy and carbon required to construct a new building.
The before and after images to the right show a historic building at the former Holman’s No.3 Engineering Works at Trevu Road, Camborne. This site contains unlisted historic buildings protected
from demolition through Conservation Area designation. The historic buildings were retained and converted with THI funding as
part of an affordable housing scheme which also contained new buildings. Retaining rather than demolishing the historic buildings added character to the overall scheme which received a
commendation from the Cornish Buildings Group Design Awards in 2013. The scheme also won a Cornwall Sustainability Award in
2012, a South West and Wales RICS award in 2013 and was voted as one of the UK’s top 50 affordable housing developments by
sector magazine Inside Housing.
Main contents
Before and after photos of part of redeveloped former Holman’s No.3 Engineering Works at Trevu Road, Camborne.
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2. The impact of climate change on historic Cornish buildings
Main contents
2.4 Heat loss Over 60% of domestic energy is used for heating as shown in the diagram to the right. Heat is lost through the building envelope,
mainly through the walls and roof. Heat in old buildings is lost through air leakage and conductivity. Air leakage occurs in gaps
through windows and doors, cracks in walls and junctions between different building elements. Thermal conductivity results in heat loss through the fabric of a building. Air tightness is more critical
than insulation as heat is lost much faster through draughts than through conductivity. Historic buildings differ and require different
solutions to reduce heat loss. The diagrams below show break-downs of heat loss through building fabric. The four examples of heat loss through traditional building fabric below show how heat
loss differs from building to building.
Source: www.scotland.gov.uk - The Key Behaviour Areas - Home Energy
(Data from DECC (2013) Energy Consumption in the United Kingdom,
Domestic Data Tables)
Heat losses through building fabric
(Figures from Energy Saving Trust)
Typical data for all dwellings Examples of measured data from four traditional buildings
2.5 Reducing energy use and carbon
emissions in historic buildings
Reducing energy use and carbon emissions in historic buildings provides sustainable benefits by minimising environmental
pollution and mitigating climate change. It also makes properties more comfortable to live in and provides potential savings in
energy bills.
Awareness is needed of the ways we use energy as well as a
desire to use less. Consideration should be given to reducing energy use and being more energy efficient; reducing waste and
switching to low carbon energy supplies.
A systematic ‘whole building’ approach to energy efficiency helps to identify the most appropriate improvements to a building or household. This approach should take into consideration the way
the building is used and the performance of its fabric / building services. Available resources and short, medium and long term
opportunities to make improvements (e.g. when a kitchen or bathroom is going to being refitted) also need to be taken into account.
First steps should always be to understand how a building works
by considering its:
Location
Construction and condition
Building services
Heritage values and significance
Occupant behaviour
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2. The impact of climate change on historic Cornish buildings
Main contents
Location
Cornwall is a narrow, exposed county surrounded by coastline. It is subject to extreme and changeable weather conditions
particularly in coastal and hilly areas. Location, orientation and exposure to sun, wind and rain affects a building’s fabric and energy use. South facing elevations benefit more from heating
from the sun while south westerly facing elevations feel the force of strong winds and horizontal driving rain. Weather proofing
buildings in exposed areas in order to keep walls dry should be considered before trying to insulate internal areas.
Construction and condition
Historic buildings differ in their construction, insulation, thermal mass and air tightness. A dressed stone wall with tight mortar
joints, for example, performs differently to a composite wall built of random rubble. Regular or lack of maintenance also affects
performance of external walls, roofs, floors, windows and doors.
Historic building fabric will often perform better than assumed. RdSAP consistently over estimates energy use in traditional build-ings. Default U-values for solid walls used in energy assessments
have also been found to be generally higher than U-values obtained from in situ measurements. Evidence also exists of
retrofit projects where solid wall insulation has been installed not fully understanding a building’s physics. This has led to problems with condensation, summer overheating and loss of benefits from
heat retention and the cooling capabilities of solid walls. Poor installation of energy saving measures and inadequate skills
training for their installation can also be problematic.
Building services
Before making physical alterations to building fabric it is essential to review how the building is used and how effectively its heated. Energy efficiency will be affected if building services do not oper-
ate as intended through equipment faults or poor maintenance.
THI funded conversion works at former Forge, Trevu Road,
Camborne, buildings that were vacant for many years.
THI funded conversion works at the former Clink, Church Lane, Camborne.
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2. The impact of climate change on historic Cornish buildings
Main contents
Occupant behaviour
Occupant behaviour is a major factor in energy use. People use energy and heat rooms in different ways and properties are not
always similar (e.g. removal of internal walls and cellar and attic conversions). There is no need to maintain uniform temperatures
throughout the whole building all year round. If temperatures can be controlled when they become too hot or too cold, a better internal thermal environment can be achieved.
Summary
Consideration of the factors described above can help to plan an
effective and affordable package of energy efficiency measures that strikes an appropriate balance between conserving the heritage values of the building and reducing energy use and carbon
emissions.
The purpose of this guide is to help in this process by providing information on low to medium and high cost energy efficiency
measures for use on historic buildings. The pros and cons of individual measures are also reviewed.
Heritage values and significance
Historic buildings differ in levels of protection and in their
significance. Section 132 of the National Planning Policy Framework states:
‘when considering the impact of a proposed development on the
significance of a designated heritage asset, great weight should be given to the asset’s conservation. The more important the asset, the greater the weight should be.’
Options to improve the energy efficiency of a Listed building could
differ from those for an unlisted building. Care is needed to avoid damaging the character and significance of a historic building with
any alterations to improve thermal and acoustic performance.
3. Keeping buildings healthy and comfortable
15 Main contents
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3. Keeping buildings healthy and comfortable
3.1 Why solid walled buildings need
to breathe
Modern buildings are usually built with insulated cavity construction. External walls are non-permeable and layered to prevent moisture reaching internal rooms. Most historic
buildings have solid walls which are built from materials that can absorb and release moisture freely. The diagram on the
right shows how moisture movement in modern and historic buildings differs. For more information see:
Historic England - Energy Efficiency and Historic Buildings
The moisture buffering capacity of solid walls can help to stabilise humidity and reduce condensation on surfaces. The thermal mass of thick masonry walls also has the effect
of reducing the size of internal temperature variations by buffering changes in external temperature. This results in
increased thermal comfort, and reduced peak loads for heating or cooling installations.
When a traditional building is working as intended there is an equilibrium between ventilation, heat and moisture.
Upsetting this balance by carrying out well intentioned alterations to improve energy efficiency can harm the building fabric and adversely affect the health and well-being
of its occupants. This can also occur if a building is poorly maintained or if unsuitable, non-breathable materials are
introduced in repairs or retrofitting.
3.2 Internal moisture vapour
Not all damp in buildings with solid walls is caused by
external water penetration. Moisture vapour is produced internally by simply living and breathing and through activities such as cooking, washing and drying clothes.
Diagram showing differences in moisture movement between modern
and historic buildings. Diagram © Robyn Pender.
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3.3 Condensation and dew points
Condensation occurs when water vapour in the air makes contact with a cold surface and condenses, returning to a liquid state.
The dew point is the temperature it condenses at. It is noticeable on windows and cold external walls and can lead to mould growth
on surfaces. Interstitial condensation occurs when water vapour passes from the internal environment and condenses within a wall.
3.4 Membranes and barriers
A variety of membranes and barriers are available for use in retrofitting:
Non-woven geotextile membrane: a strong, bonded fibre sheet that allows liquid and vapour to pass through easily while
stopping larger particles. Common uses are under patios and paths as a weed suppressant and on soakaways and French
drains. They can also be used under limecrete floors.
Vapour-permeable membrane: finely perforated sheeting material that allows water vapour to pass through but blocks the
passage of water. Often installed on the cold side of insulation where some degree of waterproofing is required.
Vapour control layer (VCL): a vapour check used on the warm side of insulation to prevent interstitial condensation.
Vapour barrier: a highly vapour resistant membrane often
unsuitable for use on historic buildings. Care is needed as workmanship and punctures from surfaces often affects the vapour tightness of the barrier.
Damp-proof membrane (DPM): a strong, impermeable plastic
membrane laid under floors to prevent rising damp. Care is needed when used on historic buildings in case water is pushed
out to external walls.
3.5 Healthy buildings
Human health is directly affected by the built environment. ‘Sick building syndrome’ can result from internal temperatures,
light levels, dampness and air quality. Great care is needed when increasing air tightness in a building as it could potentially lead to
unhealthy living conditions. Inappropriate thermal insulation or materials could have a direct effect on the health of a building’s occupants. Healthy living conditions in an older building can be
achieved by using suitable breathable materials / products and controlling moisture and ventilation.
Further information
Changeworks - the health impacts of fuel poverty and living in a cold and damp home
Historic Scotland - Indoor air quality and energy efficiency in
historic buildings
NHS Choices - Sick building syndrome
3. Keeping buildings healthy and comfortable
17 Main contents
Sympathetic conversion using clay plaster, Manaccan, Cornwall. Clay plaster provides health benefits and adds character.
Works and photo by Clayworks.
3. Keeping buildings healthy and comfortable
Further information
Historic England - Energy Efficiency and Historic Buildings
Context article: dew points / condensation by Ian Brocklebank
Community Energy Plus guide to condensation and mould
SPAB - Technical Questions and Answers - Condensation
Sustainable Traditional Building Alliance - including draft Moisture Risk Assessment and Guidance.
All buildings need adequate ventilation to remove excess moisture,
reduce the risk of condensation and to maintain good healthy indoor air quality. In Cornwall regular ventilation also reduces
health problems from Radon gas. A balance is needed between ventilation, draught reduction and any additional insulation.
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A typical air brick in stone wall
of historic building, Camborne.
Hygrometers measure humidity of moisture content identifying
areas of potential mould growth . Dehumidifier.
Remote control for central
heating.
3.6 Ways of controlling moisture
Main contents
Action Reason
Ensure regular building maintenance. Reduces damp problems.
Ensure rainwater goods and surface
water drainage systems are effective.
Reduces damp and provides
long term benefits to health of
building fabric and occupants.
Ensure adequate ventilation: open
windows if condensation forms and
install extractor fans in kitchens and
bathrooms. Install air bricks to walls.
Allows condensation to evapo-
rate/removes humid air. Open
windows provide increased
ventilation and solar gain.
Open windows and secondary glazing
during the day. Traditional windows
can be fitted with window stops to
provide a form of secure trickle
ventilation allowing windows to remain
open more regularly (see page 19).
Promotes regular ventilation.
Prevents moisture build up.
Reduces mould and condensa-
tion.
Keep lids on saucepans and vent
clothes driers externally to avoid
excess moisture (see page 23).
Reduces internal damp and
damage to building fabric.
Avoid trapping moisture within
building fabric.
Reduces internal damp and
damage to building fabric.
Ensure any insulation used on internal
or external walls is permeable.
Allows solid walls to breathe.
Avoid cold bridging (heat loss at
junctions such as window reveals)
when insulating.
Reduces condensation.
Dehumidifiers can be used to remove
excess moisture although this is not
an energy efficient option.
Reduces internal moisture.
3.7 Ventilation and security On traditional double hung sash windows both the top and bottom
sashes can be opened at the same time. This is a healthy arrangement that provides adequate ventilation to rooms.
Security is still possible on traditional windows with appropriate ironmongery. Sash window stops fixed slightly above the meeting rail
are an easy way to allow ventilation but maintain security. They provide a form of trickle ventilation without cutting through the window frame.
Ventilation can also be provided by air bricks, grilles, appropriate ridge
and eaves ventilation and by retaining and reusing existing chimneys.
Existing chimneys should not be permanently blocked and flues should be opened in the summer to assist cooling and reduce dampness in the flue. If not in use, chimneys should be vented to help air circulation
within rooms. Chimney balloons can reduce draughts to chimneys while still allowing ventilation. Before carrying out any works to flues and
chimneys seek further advice from the Fire Service.
19
Traditional sash window installed at 3-5 Tolgarrick Road, Tuckingmill allows ventilation at both top and bottom
3. Keeping buildings healthy and comfortable
Main contents
Further information
Historic Scotland - Ventilation in traditional houses
SPAB Briefing - energy efficiency in old buildings
Buildingconservation.com - fireplaces, chimneys, fire protection
Thatched Owners Group
Window stops fixed either side above the meeting rail of traditional
sash windows allow a secure form of ventilation.
3.8 Trickle ventilation A trickle vent is a small opening on a window or door which allows
internal spaces to be naturally ventilated when windows or doors are closed. On new windows this normally involves cutting a ventilation
slot through the top frame. This can look unsightly on traditional sash windows. It is possible, however, to provide neat, discreetly concealed trickle vents by cutting a vent slot in the underside of the top case of
the sash and venting through the top case as shown in the sketch and photographs on this page. For new build dwellings or extensions please
refer to Approved Document F of the Building Regulations.
20
3. Keeping buildings healthy and comfortable
Main contents
Neat slot
cut from
outer face
of top sash
and through
case
Chamfered
termination
to slot in top
sash
Fixed insect
mesh
Hit-and-miss
trickle vent
to inside of
sash Outside Inside
Front elevation
Section through box sash window
4. Reducing energy consumption
21 Main contents
4. Reducing energy consumption
4.1 Introduction Older buildings vary in construction, character, location and orientation. As such they may require different ways of improving
their energy efficiency. Before making any physical alterations to the fabric of a building it is essential to review how the building is used and how effectively it is heated (as highlighted in Section
2). Occupant behaviour and maintaining the building and building services in a good condition are major factors in reducing energy
use. Such a review will help establish what measures need to be taken to improve energy efficiency.
The aim with any measures is to find the best balance between reducing energy use, carbon emissions and preserving the
heritage value of a building.
22
4.2 ‘Trigger Points’ for retrofitting
Many energy efficiency measures can be carried out with little disturbance to the building or its occupants. Others are more
disruptive and opportunities to carry them out might occur only occasionally. Installing a new roof, for example, might give an
opportunity to install insulation from above which would be beneficial for attic conversions. Internal wall insulation is cheaper to install and less disruptive if carried out at the same time as
other renovation works. A change in building ownership could also be a trigger for carrying out energy efficiency improvements.
A whole house approach to saving energy is recommended.
Inexpensive and less intrusive improvements should always be considered first before more costly and potentially harmful works. See the following link for more information:
Westminster City Council - Retrofitting Historic Buildings for
Sustainability
4.3 Reasons to retrofit Research by the National Energy Foundation for social housing has shown that difficult or expensive to heat premises are more likely
to be under-heated and suffer from damp and condensation problems. This increases maintenance/repair costs for property owners and occupant dissatisfaction. In rented properties it can
lead to rent default and associated lost revenue due to more frequent tenancy change as well as increasing the workload of
local authority housing staff. In addition, the extra heating required for poorly insulated buildings proportionately increases the carbon dioxide (CO2) emissions associated with the buildings’
heating system.
Retrofitting requires careful consideration of the interrelationship between ventilation, heat and moisture to avoid unintended
consequences that might be harmful to human health or to the fabric of the building.
Further information
Changeworks - energy and fuel poverty
Main contents
Drying clothes outside avoids the expense of using tumble driers that also contribute to internal condensation.
4. Reducing energy consumption
23
4.4 Simple ways to reduce energy use
Ensure building fabric and services are in good repair and properly maintained to maximise performance.
Reduce draughts through doors, windows, flues and other
leaky parts of the building envelope.
Close doors to retain warmth in occupied rooms. Install heavy
curtains and thermal blinds to reduce heat loss. Draw curtains and close blinds/shutters at night.
Consider lower risk insulation opportunities such as loft and
floor insulation and secondary glazing.
Consider wall insulation only after less invasive works have been explored or implemented.
Install low energy lighting and heating systems.
Turn lights and appliances off at the socket when not required and avoid leaving appliances on standby.
Insulate your hot water cylinder.
Fix leaking taps and ensure they are fully turned off.
Have shorter showers; consider a high quality aerating shower and taps.
Install energy efficient appliances when the existing
appliances need replacing. Check the EU energy label or buy ‘Energy Saving Trust’ recommended products.
Make sure you fully load your washing machine and try to dry clothes outside.
Don’t boil a full kettle if not necessary. Use lids on saucepans
to speed up cooking, reduce energy use and condensation.
Defrost your freezer to increase its efficiency.
Wear more clothes in the winter and turn the heating down.
Consider use of renewables.
Further information
Community Energy Plus - Reduce your Energy Bills
Community Energy Plus - Films
Community Energy Plus - Factsheets and Leaflets
Historic England - Saving Energy
Poor maintenance can lead to damp problems in historic buildings.
Main contents
Action Reason
Heat house constantly at a lower
temperature.
Allows the dense material of the
house time to absorb heat and
release it slowly.
Alternatively, heat main rooms
with greater intensity. Unoccupied
rooms don't need as much heating
as occupied rooms.
Allows main rooms to be kept at
a comfortable temperature while
other rooms can be heated less.
Familiarise yourself with your
heating system. Install more sensi-
tive heating controls such as ther-
mostatic radiator control valves.
Turn off radiators in rooms that
aren't being used and close doors.
Allows appropriate temperatures
to be maintained throughout the
house. Prevents over-heating.
Tailors heating to the way
occupants use the building.
Use existing fireplaces and install a
wood burner if a good source of
fuel is available. Make sure flue is
properly lined and be wary of fire
risk in thatched properties.
Chimney breasts are designed to
store heat and release it slowly.
Rest of the flue system distrib-
utes heat to upper floors in
similar manner. Chimneys also
help internal evaporation.
Install an energy-efficient
condensing boiler.
Improves efficiency of heating
system, reducing running costs.
On alterations to large historic
buildings take simple measures to
improve efficiency of heating
systems. Lag hot water cylinders
and pipe work. Consider combi
boilers and local water heaters to
reduce pipe run lengths.
Improves efficiency of heating
System, reducing running costs.
Consider use of energy audits /
assessments.
Assess performance of existing
heating, lighting and take
appropriate measures to improve
efficiency.
4. Reducing energy consumption
Easy ways to reduce energy use
24
4.5 Heating systems
Modern houses are highly insulated to reduce heat loss and respond
rapidly to heating. They are typically heated for a couple of hours in the morning and evening when the occupants are at home. Heating
regimes like this may not be suitable for many older houses with thicker walls that take longer to heat up and cool down. They can create dramatic temperature fluctuations leading to increased risk of
condensation. More information on suitable heating systems for historic buildings is located in Appendix 2.
Domestic hot water heating accounts for 25% of energy use. The efficiency of domestic hot water provision should be considered.
Smart meters, energy meters and other investigative tools can help
to assess and plan an effective heating regime for your property. Smart meters can be locally bought from around £20 and will be
offered by the Government to every home in England, Wales and Scotland by 2020. More information on smart meters is on the Energy Saving Trust website. Information on energy assessments
can be found in Section 1.10.
There is no need to return to 18th century living arrangements, but small behavioural changes should lead to a more comfortable home
and lower energy bills.
Main contents
Typical Energy Meter Thermostatic radiator valve
4. Reducing energy consumption
4.6 Draught reduction
The table below shows inexpensive and unobtrusive methods of
draught reduction that are easy to install. Reducing draughts will make a building easier and cheaper to heat. Good draught proofing
should be durable and inconspicuous. Maintaining adequate ventilation is essential in older buildings.
Further information on draught proofing and options to upgrade existing windows is available in Section 5.2.3
Action Reason
Draught-strip your doors,
windows and floors and install
chimney balloons.
Inexpensive ways to reduce
draughts. For more information see
Section 5.2.3 (Draught proofing).
Install secondary glazing,
(permanent or seasonal).
Reinstating or installing shut-
ters, blinds and curtains can
also help reduce draughts.
A cost-effective way to improve
energy efficiency. Secondary glazing
is also effective at reducing noise
and can be installed with acoustic
glass (see Section 5.2.4).
Open curtains, shutters and
blinds during the day and
close them at night.
Reduces draughts, maximises solar
gains during the day and retains
heat during the night.
Close internal doors when
temperatures are cold.
Reduces effect of draughts.
Retains heat in each room.
Use doorway draught exclud-
ers (such as sausage dogs).
Cheap way of reducing draughts,
especially on loose-fitting doors.
Lay carpets on floors or use
rugs where carpets are not
suitable.
Adds an additional thermal layer to
the floor. Reduces draughts.
Hang tapestries or other
fabrics from walls.
Adds an additional thermal layer to
the wall, improving comfort.
Reduces radiant heat loss.
25
Chimney balloon for fireplace. Photo courtesy Historic Scotland
Draught excluder on traditional door.
Main contents
5. Building fabric improvements
26 Main contents
5. Building fabric improvements
5.1 Introduction This section provides examples of sympathetic products and
materials for upgrading historic buildings and covers:
Window upgrading
Roof insulation
Floor insulation (ground and intermediate floors)
Wall insulation (external, internal and cavity)
5.2 Windows Original windows in historic buildings should be preserved as they provide significant architectural and historic character. This is reflected in the large number of unsuccessful planning appeals for replacing traditional windows in historic buildings. Repairing and maintaining original windows is always preferable to removing and replacing them. Replacing traditional windows on your property can reduce its market value.
Image provided by English Heritage
5.2.1 Improving the performance of
traditional windows
The thermal performance of an original window can be improved easily and cost effectively without affecting its character. The
table below shows options to upgrade single glazed windows with comparative U-values. It shows that original windows can be retained and upgraded to a thermal performance up to or near
the standards required by Part L of the Building Regulations.
These options will be cheaper than installing new double glazing throughout your house, while still retaining character and
providing highly effective improvements to thermal performance. The measures below can also be combined to further increase performance.
A number of these options have been trialled and monitored as
part of the Camborne, Roskear, Tuckingmill Townscape Heritage Initiatives. Results of this monitoring is included in Appendix 1.
27 Main contents
5. Building fabric improvements5.2.2 Repairs and maintenance
Old windows often look in worse condition than they actually are
and can easily be professionally overhauled and draught proofed. Draughts can be reduced by as much as a third if windows are repaired and maintained properly.
Many good long lasting paints are now available which can reduce
maintenance periods. Linseed paint, for example, can last up to 15 years which is comparable to the lifespan of a uPVC window. Section 6.2.8 provides information and costs on appropriate and
sustainable finishes for timber windows.
Pros Cons
Windows often look worse than they are and often
only the cills and lower frames need replacing.
Allows windows to open, improving ventilation.
Retains original fabric, increasing window life
Reduces amount of further improvements required
Resin repairs / reclaimed timber can improve the
quality of repairs and significantly extend the
lifespan of the repair.
Good quality paints and stains now available which
significantly reduce maintenance periods.
Maintaining original glazing adds character.
Requires regular
maintenance and
painting.
Maintenance of
high level detailing
sometimes difficult.
Process Capital Costs
(Supply & install)
Lifespan in
years
Typical overhaul of sash
window using splicing £160-650 100 plus
New hardwood cill
New softwood cill
Reclaimed wood cill repair
£160
£110
£55
Up to 50
Up to 30
Up to 20
Typical overhaul of sash window using resin repair
£55- £185 (resin only)
20-25 (resin only)
Replacement timber sash windows
£990 - £1,400 35 - 100
Costs / lifespan (based on typical sash window 800x1000mm)
Further information
Historic England - Traditional Windows: repair, care,
maintenance
Historic Scotland - Sash and Case Windows guide
Buildingconservation.com - articles on window repair
Technical Q and As from SPAB
Greenspec - search ‘timber preservation’
THI funded traditional timber repairs using resin at junction of
scarfed and original timber, Trelawney Road, Camborne.
28 Main contents
5. Building fabric improvements
29
THI funded resin repairs to original timber windows and doors,
Trelawney Road, Camborne
Main contents
5. Building fabric improvements5.2.3 Draught proofing
Draughts account for 15-20% of all heat lost in old buildings. They can come from windows, doors, loft hatches, electrical
fittings on walls and ceilings, suspended floors, pipe work leading outside, ceiling-to-wall joints and chimneys/fireplaces.
Draughts can be reduced using appropriate gap fillers and weatherising rubber tubes or pile brushes. Care is needed to
allow sufficient ventilation to provide fresh air and remove moisture and pollutants. More ventilation is needed in wet rooms,
kitchens, bathrooms and rooms with fireplaces.
A draught proofed house will feel more comfortable at lower
temperatures due to the reduction of any wind chill factor. This reduces heating requirements, increases savings and efficiency. If
a window rattles it is likely to have gaps and draughts. Draught proofing reduces any rattling making the window easier to open which allows it to be used more frequently for ventilation.
Above: draught proofed sash window. Diagram to right: draught
proofing examples. Photo and diagram courtesy English Heritage.
30 Main contents
5. Building fabric improvements
Pros Cons
Reduces uncontrolled ventilation
in houses.
Reduces heat demand.
Reduces heating bill.
Reduces carbon emissions.
Easy to install.
Draught proofing carried out as
part of a window overhaul allows
sash windows to open easily
without rattling.
Helps retain original fabric.
Can sometimes affect character
of windows and doors.
Draught proofing windows where
secondary glazing has been
installed can cause condensation
on outer glazing.
Chimneys should not be
permanently blocked. Flues
should be open in summer to
assist with cooling and reducing
dampness in the flue.
Costs / savings / payback Figures from Energy Saving Trust
Process Typical
Costs
Savings per year Payback
in years
Draught proofing
around windows,
doors, etc.
£130 DIY
£260
Professional
Draught proofing: £55
Heating saving: £60
Total: £115
1 – 2 DIY
2 – 3
Professional
Filling gaps
between floor and
skirting board.
Around £27 Around £20 Around 1
year
Chimney Sheep
Draught Excluder
£21 - £52 1% - 5% per annum
on heating bill
1-5
Solutions and materials
Area Solution Cost (materials only)
Windows Self adhesive foam strips – cheap
option.
Professionally installed seals – more
expensive but longer lasting.
Replacement traditional windows can be
rebated to allow draught proofed seals
to be fixed.
£1 / m plus
£5 plus
Doors Keyhole cover.
Letterbox flap with brush.
Draught exclusion strip along bottom.
Foam, brush or wiper strips along sides.
£5 plus
£15.50 plus
£10.50 plus
£1 / m plus
Chimneys /
Fireplaces
Install chimney balloon/chimney sheep
or fit register plate with vent grille that
can be opened or closed.
£15.50 plus
Floorboards Filler, decorators caulk.
Proprietary flexible seals.
£15.50 plus
Loft
Hatches
Draught proof as doors and provide
insulation on back.
£1 / m plus
Further information
Historic England - Draught proofing general information
Historic England - Draught proofing windows and doors
Historic England - open fires, chimneys and flues
Energy Saving Trust - draught proofing your home
The greenage - draught proofing chimneys
5.2.3 Draught proofing (continued)
31 Main contents
5.2.4 Secondary glazing Secondary glazing has improved in recent years and can open in a
similar way to a traditional sliding sash window. This gives it an unobtrusive appearance. It is a good way of providing thermal
improvements, particularly where low emissivity glass is used. Secondary glazing avoids having to remove the window’s original glass. It is reversible, can be easily cleaned and is a very effective
way of reducing noise especially if acoustic glass is used. Condensation risks can be reduced by not draught proofing original
windows and relying on draught proofing secondary glazing.
5. Building fabric improvements
Costs / lifespan Based on typical sash window 800x1000mm
Process Capital Costs
(supply & install)
Lifespan in
years
Secondary glazing with
magnetic strip fixing
£270-£435 90
Secondary glazing with
acoustic glass
£340-£390 90
Secondary glazing with
standard glass
£270-£325 90
Secondary glazing with acrylic £110-£215 40
Transparent film (DIY option) £10-£22 15
Secondary glazing with low
emissivity glass
£200 90
Pros Cons
No need to remove original windows.
Kits can be purchased and installed DIY.
Cheaper than new double glazed units.
Modern secondary glazing is unobtrusive,
easy to open and clean. It can open in a
similar way to a sash window. Opening sash
and secondary glazing together has visual
benefits and makes ventilation easier.
Option to remove secondary glazing in the
summer.
High quality noise reduction through larger
air gap.
Good option for buildings fronting highways.
Provides additional security.
Some additional
reflections when
viewed from outside.
Older secondary
glazing often looks
clumsy.
May interfere with
operation of internal
shutters.
THI funded secondary glazing fixed through magnetic strips, Cross Street, Camborne.
32 Main contents
5. Building fabric improvements
Further information
Buildingconservation.com - Secondary Glazing
Historic England- Secondary glazing for windows
Historic England - Research: thermal performance of traditional windows
Centre for Sustainable Energy - Secondary Glazing
Historic Scotland - Thermal performance of traditional windows
Storm Windows - bespoke secondary glazing for historic buildings
A DIY secondary glazing solution at the Old Rectory, North Cornwall using aluminium profiling and anti reflective Perspex fixed with magnetic tape.
The secondary glazing is installed in autumn and removed in spring. Care is needed to ensure that adequate fire escape is still possible from internal rooms.
33
Secondary glazing can be easily and cheaply installed. Acrylic panels can be clip fixed to internal timber frames
as shown here at converted former Carpenter’s Shop at Heartlands, Pool.
Main contents
5.2.5 Shutters Internal shutters were historically used to retain heat and improve security and privacy. They are an important feature of many
historic buildings and add character to interior rooms. They often remain in historic buildings and can be easily and cheaply restored
or reinstated.
Thermal performance can be increased through draught proofing and insulating shutter panels on new shutters (see images below).
Energy monitoring carried out as part of the Camborne THI (see Appendix 1) indicated that reinstated shutters could reduce annual energy bills by 5-10%
5. Building fabric improvements
Pros Cons
Significantly reduces heat loss.
Cheap solution if shutter already installed and only draught proofing required.
May be able to be installed DIY.
Looks good and adds character to a room.
Draught proofing shutters increases performance.
Offer reasonable noise protection.
Option to install thermal shutters.
Increases security.
Shutters usually left open during the day, increasing heat loss.
Care needed not to trap fingers when opening and closing shutters.
Could damage window or reveal if not adequately restrained at reveal or stops for locking bars not fixed.
Process Capital Costs (supply & install)
Lifespan in years
Restored existing original timber shutters
£57-£160/nr 10-15 until another
restoration needed
Replacement original timber shutters
£160 - £325/nr 30-40
New purpose made timber shutters
£215 - £540/nr 30-40
New purpose made thermal timber shutters
£865/nr 30-40
Extra over draught proofing for shutters
£80 - £160/ nr 10-20
Costs / lifespan Based on typical sash window 800x1000mm
New shutters should be rebated on both sides of each individual
panel, extend to the internal window cill and be accurately restrained at window reveals.
34
Insulating shutter panels Photograph: Historic Scotland.
Main contents
THI funded draught proofed
shutters, 3 Penlu, Tuckingmill
Traditional timber shutters installed as part of THI works.
Above: reinstated traditional shutters at 3 Penlu, Tuckingmill.
Right: new shutters installed at Trevu Road, Camborne.
5. Building fabric improvements
35 Main contents
5. Building fabric improvements
5.2.6 Thermal blinds and curtains
The use of modern insulated or traditional heavy lined curtains or reflective and/or insulated blinds is a simple and cheap way to
improve the thermal performance of windows.
Thermal roman blinds, made of flexible fabrics, including low emissivity films, ‘Thinsulate’ insulation and Aluminised Mylar (space blanket) are available. These can be sealed to existing
window frames using powerful magnets and can substantially
reduce heat loss and draughts from single glazed windows.
Clear insulating blinds are also available which can be used in
addition to curtains.
Thermal blinds and curtains would often be used anyway in a historic building and can prove an easy and cost effective way of
improving efficiency while retaining the character of an internal
space.
Suppliers
The Thermal Blind Company - thermal and roman blinds
Insu - clear insulating and draught proof blinds
Natural Curtain Company - thermal curtains
Sail Shade blinds for conservatories
Pros Cons
Cheap option to upgrade thermal
performance.
Good range of available colours.
Adds character.
Blinds and curtains would usually be
used anyway.
Clear insulated blinds allow light to enter
and can be left closed.
Risk of mould.
Magnetic fixing strip for
thermal blinds needs
careful detail to avoid
looking clumsy.
Lack of privacy when
blinds open.
Process Typical Costs
(Supply only rates)
Lifespan in years
Thermal blinds £32 - £105/nr 10
Clear insulating blinds £32 - £105/nr 10
Thermal curtains £42/nr 10
Thermal linings for
existing curtains
£17/nr 10
Standard blinds £16 - £210/nr 10
Standard curtains £16 - £210/nr 10
Costs / lifespan
36
Thermal roman blind from
the Thermal Blind Company. Clear insulated blind from
www.insu.co.uk.
Main contents
5.2.7 Double glazing
Replacing windows should only be considered on historic buildings
where existing windows are truly beyond repair or are inappropri-ate replacements. It is essential to retain original fabric and glass
wherever possible.
Single glazed traditional timber windows are usually the only acceptable option for listed buildings. Recent appeal decisions support this view. Good quality timber double glazed windows
may be appropriate for extensions to listed buildings and unlisted buildings in Conservation Areas. uPVC double glazing is always
inappropriate for use in historic buildings and is harmful to produce. uPVC glazing bars cannot replicate original detailing and are often either too bulky or ‘stuck on’.
Double glazing is more appropriate on larger Victorian windows
as it is easier to replicate larger original glazing bar details. It is impossible to replicate glazing bars on smaller paned Georgian
windows. When used on historic buildings double glazing should be in timber and consideration should be given to colour coding spacing bars to match the paint finish of the window and puttied
beading.
Slim double glazed units are now available with units 10-12mm thick. These units have inert gas sandwiched between the two
panes of glass which provides thermal benefits. Slim profile double glazing is not suitable for many listed buildings as the glazing rebates are too small to accommodate the thicker units.
They are more suitable for use with heavier Victorian and Edwardian profiles. The increased weight of the glass can strain
parts of windows and cause problems balancing sashes. This sometimes leads to use of spiral balances as opposed to traditional lead weights.
Testing of slim profile double glazing by Historic Scotland shows
that its thermal performance is not as effective as secondary glazing.
5. Building fabric improvements
Process Capital Costs
(supply and install)
Savings per year
Payback in years
Lifespan in years
Standard timber double glazed sash
£1,025 £166 6 10 - 20
Slim double glazed timber sash
£1,400 £171 9 10 - 20
Typical single glazed timber sash
£1,295 £90 14 60 plus
Typical uPVC double glazed sash
£1,075 £40 10 - 20 25
Histoglass (Float Glass) double glazed
£1,015 £170 35-100 7
Costs / Savings / Payback Based on typical sash window 800x1000mm
Pros Cons
Improves thermal performance.
Slim units are available.
Easy to open.
Paints and stains are now available that will reduce maintenance periods.
Glazing bars too bulky or ‘stuck on’.
Slim units very expensive and reflective.
Extra weight of slim units results in thicker glazing bars and spiral balances.
Putty needs to be sound and maintained when slim double glazing is used.
Loss of historic fabric and glass.
Guidance
Historic England - Energy Efficiency in Historic Buildings
Historic England - Thermal performance of timber sash windows
Historic Scotland - technical report on slim double glazing
Historic Scotland - Slim-profile double-glazing in listed buildings
Slim double glazing suppliers
Slimlite
Histoglass
37 Main contents
5. Building fabric improvements
Timber double glazed window with chamfered timber mock putty beading to reduce glazing bar size (top left) and double glazed
timber sash windows at Mill Street, St Day (above right/below) showing the benefit of coordinated colour schemes in a terrace.
38
THI funded slim double glazing.
Main contents
5.2.8 Types of glass
A number of options are available for glazing windows in historic
buildings. Retaining original glass is always preferable as it adds character to traditional windows and may be of heritage value in
its own right. Historic glass can also be incorporated into slim
profile double glazing - see the Histoglass website.
Heat loss occurs around the edge of a window. If putty beading is
well maintained, retained original glass should not unduly
contribute to heat loss through windows. Other types of glazing are available that provide additional security and compliance with
Building Regulations.
Process Pros Cons Costs per m² (Supply only)
Standard glass
Easily available.
Lacks character and not as strong as others.
£57
Reclaimed glass
Original fabric, adds traditional character.
Very thin. Expensive.
£261
Low E Glass
Improved U value. Increased passive solar gains.
More expensive than standard glass.
£168
Laminated glass
Safety glass holds together when shattered.
Difficult to cut. £73
Toughened glass
Strong safety glass crumbles rather than splinters when broken.
Possible security risk through shattering.
£68
Cylinder/heritage glass
Adds traditional character by replicating original detailing.
Expensive. £157
Acoustic glass
Reduces noise, strong, absorbs harmful UV rays, improves energy efficiency
Expensive. £185
Pros / Cons / Costs
Low E glass
Hard Coat Low E glass has a coating applied at a high
temperature which creates a durable surface which uses passive solar gains and increases thermal performance. There may be a
slight haze visible at certain angles which might restrict its use in some listed buildings. Low E glass can be mounted in secondary
glazing, allowing original glazing to be retained.
Further information / suppliers
Historic Scotland - Maintaining traditional glass guide
Cornwall Glass and Glazing Co.
London Crown Glass Company - conservation glasses
Pilkington - manufacturer of Low E Glass
Tatra Glass - imported cylinder glass
Histoglass - slim profile double glazing
Sash Window Specialist - Acoustic Glass
5. Building fabric improvements
New cylinder glass used
at Heartlands, Pool.
Original glass at Godolphin House,
near Helston.
39 Main contents
5. Building fabric improvements
40
5.3 Insulation In older houses care is needed when choosing insulation as it must allow for moisture transfer through the building fabric. Natural or
synthetic ‘breathable’ materials are suitable for solid walled buildings. Natural materials may have lower thermal performance
figures than their synthetic counterparts, but are more compatible with historic building fabrics.
Problems often occur when materials designed for use with modern construction systems are used in old buildings. Many of these act as
a barrier to moisture and do not take into account the need for old solid walled buildings to breathe.
Poor choices of insulation materials and techniques could result in trapped moisture within the fabric of a building. This can result in
mould and decay which is damaging to building fabric as well as the health of occupants.
Installing appropriate levels of insulation can reduce heat loss and
energy demand leading to savings in money and carbon emissions. This section highlights appropriate products and provides performance data, costs and web links to enable further research.
Inappropriate external insulation. Photo English Heritage.
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Wood fibre insulation boards. Photo English Heritage.
Wood fibre insulation boards, Rosewarne House, Camborne.
5. Building fabric improvements
External insulation to these terraced properties in Camborne has resulted in loss of original material and architectural character
especially to doors and windows.
41
5.4 Roof insulation
In an uninsulated building, 25% of all heat lost is through the
roof. Insulating the loft, attic or flat roof (including lagging water pipes and tanks) is a simple way to reduce heat loss as well as
saving money and carbon. Roof insulation is easy to install, has a large DIY market and is cost effective with a lifetime guarantee on most products of 40 years or more.
Costs / Savings / Payback (Energy Saving Trust 2012)
5. Building fabric improvements
Further guidance
Historic England - Insulating Roofs in Historic Buildings
Community Energy Plus - Loft Insulation (Guide for Homeowners)
Energy Saving Trust - Roof and loft insulation
Loft Insulation (0 – 270mm)
Loft insulation (100 –270mm)
Savings per year Up to £175 £25
Installation cost £110 to £380 £110 to £380
Payback time Up to 2 years 4 years plus
DIY cost £57 to £370 £57 to £370
Payback time Up to 2 years 2 years plus
Carbon dioxide
saved per year
Around 720kg Around 110kg
42
Sheepswool roof insulation being laid. Photo courtesy of Mike Wye and Associates Ltd.
Suitable materials for roof insulation include cellulose, sheep’s
wool, hemp and flax (see insulation table in Section 5.7 for costs and technical information).
Check if bats are present in the roof space as this could affect
building programmes. For information: Natural England - Bats
Main contents
Pros Cons
A major area of heat loss is through
the roof which is reduced with
insulation.
Reduced heating bills.
Carbon savings.
On Building Control applications extra
insulation in roof can avoid need to
upgrade single glazed windows.
Easy to install and can easily be
carried out during re-roofing works.
Some roof spaces are hard to
access.
Blocking roof space ventilation
with insulation can cause
condensation which could lead
to decay in roof structures.
Breathable roof felts, sealing
roof hatches and fixing vents to
slates, eaves and ridges can
reduce condensation.
The following table shows savings under two scenarios:
installation of any insulation where there has been none.
installation in addition to existing insulation.
5. Building fabric improvements
5.5 Floor insulation
Insulating ground floors can help reduce heat loss. On solid
ground floors installing a ‘floating floor’ with integral insulation is potentially damaging to internal features of historic buildings such
as floors and skirting boards. Limecrete can provide a vapour permeable alternative to a solid concrete floor with or without a damp proof membrane. Insulated clay aggregates can be
incorporated into the slab rather than using sand to insulate a limecrete floor. Glass foam granulates are another sustainable
option for insulating building floors.
In Listed buildings original fittings such as skirting boards and other timber detailing should be retained rather than replaced wherever possible.
For suspended timber ground and intermediate floors the least
damaging solution is to carefully raise the floor boards and insulate the void between joists. This is especially important for
floors on upper rooms above lower rooms with historic plasterwork cornices and ceiling roses. It is essential to maintain adequate ventilation in suspended ground floors after insulating.
If the floor in your property is suitable for being insulated, the
following information should be of help.
Costs/Savings/Payback (Energy Saving Trust 2012)
Guidance/Suppliers
Historic England - Insulating floors in Historic Buildings
Energy Saving Trust - Floor insulation
IHBC - New developments in insulated, breathing lime floors
Mike Wye and Associates Ltd - search ‘Limecrete Floor Systems’
Mike Wye and Associates Ltd - search ‘foam glass aggregate’
Tŷ Mawr Lime Ltd - search ‘Sublime® flooring system’
Tŷ Mawr Lime Ltd - search ‘recycled foamed glass’ 43
Figures below are supply and install rates
Process Annual Saving
Cost Payback time (years)
Carbon dioxide savings per year
Floor insulation – timber floor (between or over timbers)
£60
Arround £110 (DIY) Arround £835 (Professional)
Arround 2 (DIY) Around 12 (Professional)
Around 240kg
Solid floor insulation (rate includes 150mm reinforced concrete slab, screed and insulation)
£60
£57 / m²
Depends on floor area-typical 50 m2 floor will take 40 years
Around 240kg
Limecrete - including membrane, insulation and limecrete slab
Same as concrete floor
£88 / m²
Depends on floor area-typical 50m2 floor will take 65 years
40% over concrete
Insulated clay aggregate
Same as concrete floor
£110/ m²
Depends on floor area-typical 50 m2 floor will take 85 years
45% over concrete
Glass foam granulate sub floor - insulation only
£60
£21-£26/m² based on 160mm thickness
Depends on floor area - typical 50 m² floor will take 50 years
Around 240kg
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Pros Cons
Reduces heating bills.
Carbon savings.
Creates a warmer, more comfortable
floor.
On Building Control applications
extra insulation on floors can avoid
need to upgrade single glazed
windows.
Carpets and thermal underlays can
be an easy way of insulating
suspended or solid floors.
Blocking ventilation flows in
floors can increase moisture.
Original doors and skirting
boards can be affected when
insulating solid ground floors.
5. Building fabric improvements
5.5 Floor insulation
44
Limecrete floor slabs installed at Grade I Listed Godolphin House,
near Helston, allow the floor to breathe
Floorboards being re-fixed over an air and vapour control
layer laid over insulation within the floor. Image English Heritage (© John McKay Bolsover DC.).
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5. Building fabric improvements
5.6 Wall insulation Many historic buildings have thick solid walls of stone, brick or earth which vary in condition and quality of construction. Some
well-built walls retain heat but others account for as much as a third of the heat lost from a building. Many old buildings have
good thermal mass which helps to absorb, store and release heat over time. Any defects or damp problems in solid walls should be remedied and walls allowed to dry out before installation of any
wall insulation.
External and internal walls are often a significant feature of a historic building, so any wall insulation needs to be sympathetic
to the character of the building.
The following sections include information on external, internal
and cavity insulation and apply to timber framed as well as solid wall construction.
Details of costs, lifespan and thermal conductivity are combined
in a table at the end of this section.
Insulation costs / savings / payback
5.6.1 External wall insulation External insulation can keep solid wall construction warm and reduce the risk of condensation. Unfortunately for Listed buildings
and historic buildings in Conservation Areas, external insulation is often unacceptable as it alters the architectural character, detail and historic value of the building as well as the character of its
surroundings. This conflicts with core planning principles of the NPPF that advise to:
‘conserve heritage assets in a manner appropriate to their
significance so that they can be enjoyed for their contribution to the quality of life of this and future generations’
There are cases where slate hanging and lime renders are acceptable traditional external finishes that might be used in
addition to external wall insulation.
Further information about external wall insulation including costs is available at the end of this section.
Pros Cons
Minimal disruption.
Does not reduce the floor
area of your home.
Improves weatherproofing
and sound resistance.
Helps airtightness.
Increases the life of your
walls by protecting
masonry.
Reduces moisture ingress.
Retains beneficial thermal
mass of solid walls.
Can be expensive: reduced costs if carried
out when external refurbishment planned.
May need planning permission.
Unlikely to be approved in historic build-
ings if it affects character and significance.
Not recommended if the outer walls are
structurally unsound and can’t be repaired.
Likely to require alteration to roof over-
hang, fascia, soffits and rainwater goods.
Affects proportions of original details
(quoins, window reveals, cills, thresholds).
Could be a less breathable end product.
Rendered surfaces will need redecoration.
Need for careful design and installation to
avoid risk of water penetration and
trapping.
45
Type of insulation Internal External Cavity
Savings per year £460 £490 £140
Total cost including
installation
£5,925 to
£9,150
£10,220 to
£14,145
£110 to £380
Carbon dioxide
saved per year
1.8 tonnes 1.9 tonnes Around 550kg
Payback time 13–20 years 20–30 years Up to 3 years
These are estimated figures taken from the Energy Saving Trust.
They are based on insulating a gas-heated, semi-detached home with three bedrooms. The average installed cost is unsubsidised.
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5. Building fabric improvements
46
Hofatex board installed as part of the Warmshell system at a property in St Buryan. The board can
be lime rendered allowing the building to breathe. Photo courtesy of Cornish Lime Company.
5.6.1 External wall insulation
Diffutherm board
Diffutherm board is a rigid insulation board made from natural wood fibres which gives good thermal and acoustic properties.
The board is hygroscopic allowing moisture control and is quick and easy to install.
Suppliers
Greenspec - search ‘Pavatex NBT Diffutherm’
Ecomerchant.co.uk - search ‘Diffutherm’
Tŷ Mawr Lime Ltd - search ‘Diffutherm’
Mike Wye and Associates Ltd - search ‘Diffutherm’
Hofatex board
Hofatex board is a softwood fibre board for use as thermal insulation and soundproofing in floors, walls and ceilings. It can
be used as part of the Warmshell system to create a breathable add on insulation to existing solid walls.
Suppliers
www.wood-fibre.co.uk - Hofatex wood fibre insulation
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5. Building fabric improvements
47
5.6.1 External wall insulation
All photos: the grade II* listed former carpenters shop at Heart-lands, Pool was insulated and clad externally (using 260mm thick rigid insulation boards between cladding). This allowed original timber boarding to be exposed internally. The shadow gap on the window reveal above subtly indicates where the new external cladding starts. The building has been converted to a café and bar serving the heritage and parkland development at Heart-lands. Completed works achieved a BREEAM score of ‘excellent’.
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5.6.2 Internal wall insulation
On many historic buildings internal wall insulation is only a viable option where the original wall lining or finishes are not present or
need to be replaced.
Internal insulation in solid wall construction should still allow walls to breathe to reduce the risk of trapping moisture in the fabric of the walls. Many good breathable products are now available which
enable sympathetic internal upgrading of historic buildings.
Internal insulation restricts heat loss through fabric and lowers the U value of a wall to a level that can comply with Building
Regulations. There is a need to balance the amount of insulation applied against the creation of cold bridges, increased condensation and reduced benefits of thermal mass.
Non permeable internal insulation requires a well fixed and sealed
vapour barrier to prevent internal moisture vapour reaching the insulation. This is difficult to achieve and vapour barriers eventually
break down. Removable internal insulation is preferable and good sustainable options such as hemp plaster and clay renders are now available.
Pros Cons
Generally cheaper to install
than external wall insulation.
Can be done wall by wall
based on convenience and
budgetary constraints /
availability.
Breathable internal insulation
is available e.g. hemp
plaster / wood fibre boards.
Hemp plaster could lead to
retention of internal features if
taken back to original wall
surface.
Does not affect external
appearance of building.
Reduction of room dimensions.
Some disruption due to removal and
replacement of skirting, door frames
and services.
Changes proportions of detailing
such as window reveals, cornicing,
skirting.
Can make it hard to fix heavy items
to internal walls – although special
fixings are available.
Any problems with penetrating or
rising damp need to be fixed first.
Technical risks not fully understood
and currently being researched.
Could encourage cold bridging and
condensation.
Could damage any hidden original
detailing such as early plaster /
paint / timber panelling.
May increase levels of damp in wall
behind insulation.
5. Building fabric improvements
48
Thermal bridging
Thermal or cold bridging is a local cold spot which can occur when thermal performance is improved in one area with the
addition of insulation, while an adjacent area is not insulated. It can occur on window reveals, concrete floor slabs, steel
lintels and metal fixings (such as screws penetrating internal plaster board and spreader plates on wall plates).
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5.6.2 Internal wall insulation
5. Building fabric improvements
49
Hempsulate used at Windmill Cottage, Trevone near St Merryn. Photo courtesy of the Cornish Lime Company.
Reed board
Reed board is a rigid building board made from natural reeds. It is suitable for use as a base for plastering on walls and ceilings as
a sustainable alternative to gypsum plasterboard. It can be used as a curved backing for plaster and to create an insulated ceiling.
Reed board prior to lime plastering. Photo courtesy of Mike Wye and Associates Ltd.
Hemp plaster
Hemp plaster is a low carbon alternative to gypsum based plasters and renders. It is made from hemp, lime and recycled
materials. It has good thermal qualities and allows walls to breathe, promoting a healthy indoor environment. As it is a
wet-applied plaster it forms an effective anti vapour control layer. There are some concerns with drying times.
Suppliers
Mike Wye and Associates Ltd - search ‘Reed board’
Greenspec - search ‘Claytec reed mats and reed boards’
Suppliers
St Astier - hemp construction
Cornish Lime Company - search ‘Hempsulate’
Tŷ Mawr Lime Ltd - search ‘Lime Hemp Plaster’
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5.6.2 Internal insulation
5. Building fabric improvements
50
Suppliers
Mike Wye and Associates Ltd - search ‘Clayboard’
Greenspec - search ‘Plasterboard’, ‘clayboard’
Passivhaus Store - search ‘Claytec’
Suppliers
Mike Wye and Associates Ltd - search ‘SecilVit cork board’
Tŷ Mawr Lime Ltd - search ‘EcoCork Board’
Cork insulation board system
This is a high performance, vapour permeable board made entirely from natural and renewable cork. It provides permeable
insulation with excellent acoustic properties. More details of cork insulation are available in Appendix 4.
Clay boards
These are composite boards made of clay, reed and hessian which offer a practical alternative to gypsum plaster board. It is
suitable for use internally in dry wall construction on walls and ceilings. It is compatible with clay and lime based plasters, helps regulate temperature and moisture and provides acoustic
insulation.
Photo courtesy of Greenspec.
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Lime rendered cork board, Rosewarne House, Camborne.
Breathable wood fibre insulation boards fixed to internal walls to upgrade thermal performance of THI funded conversion of former
‘Clink’, Camborne.
5.6.2 Internal insulation
5. Building fabric improvements
51
Suppliers
Mike Wye and Associates Ltd - search ‘Thermafleece’
Tŷ Mawr Lime Ltd - search ‘Thermafleece’
Black Mountain Insulation - manufacturers of sheep’s wool and hemp insulation
Suppliers
Mike Wye and Associates Ltd - search ‘Pavadentro’
Tŷ Mawr Lime Ltd - search ‘Pavadentro’
Internal wood fibre board
Breathable wood fibre boards are natural, renewable products made from waste softwood such as splinters and woodchips from
local sawmills. They are easy to handle, vapour permeable, have outstanding hygroscopic properties and can help create healthy living conditions. They can be recycled, composted or used to
produce heat at the end of their life.
Wool insulation
Wool insulation is easy to handle and quick to install. It can be securely fitted between studwork to fill or part fill a void and can
be used as part of a system to internally insulate solid walls. It requires a breather membrane to the inner face of the solid wall on the cold side and a vapour control layer on the warm side
before installation of wall finish. It is available in batts or rolls.
Diagram showing installation of ‘Thermafleece’ wool insulation.
Image courtesy of Mike Wye and Associates Ltd.
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5.6.2 Internal insulation
52
Hydraulic lime render with natural cork
aggregates (Secil ecoCORK Lime)
This is a vapour permeable lightweight render with good thermal
and acoustic properties. It is made from natural cork aggregates, natural hydraulic lime, lime aggregates and additions. It can be
used on exterior and interior walls and ceilings and can be finished with lime wash or mineral silicate paint.
Photo courtesy of Mike Wye and Associates Ltd.
Clay plasters
Clay plasters are a healthy, sustainable internal finish and can be a cost effective alternative to conventional plasters. They can be
applied on top of internal wall insulation. As well as providing character to internal spaces they have hygroscopic properties which means they absorb and desorb indoor humidity. This
reduces the chance of mould growth and airborne infectious bacteria and viruses, providing benefits for asthma sufferers.
They carry a significantly lower embodied energy than conven-tional and lime based plasters and paints. In Cornwall clay plasters can be sourced locally.
Guidance / suppliers
Buildingconservation.com - search ‘clay plasters’
Clayworks - unfired clay
Mike Wye and Associates Ltd - search ‘Claytec’
Suppliers
Mike Wye and Associates Ltd - search ‘EcoCork’
Tŷ Mawr Lime Ltd - search ‘EcoCork’
Natural Building Centre - select ‘lime plasters’
Greenspec - search ‘Diathonite Evolution’
5. Building fabric improvements
Main contents
Clay plasters used at at Kestle Barton, Manaccan. Works and photo by Clayworks.
ecoCORK, Rosewarne House, Camborne
5.6.2 Internal insulation
53
Thermablok Aerogel Magnesium Wall Board
Very thin, breathable thermally efficient panels used internally to upgrade solid walls, floors and roofs. They are useful where space
is at a premium and on areas of potential cold bridging such as window reveals.
The board is available in a range of thicknesses and can be
mechanically fixed to a range of materials. It offers health benefits to internal spaces. Being breathable it has a natural ability to repel
liquid while allowing the passage of water vapour. It is also offers no bacterial platform for mould growth as it is hydrophobic not being affected by age or moisture.
5. Building fabric improvements
Main contents
Calsitherm Climate Board
An insulation board made from calcium silicate, a micro porous building material with effective insulating properties. The board
helps regulate humidity and inhibits mould growth creating healthier internal living conditions. Its resistance to mould make
it useable on vulnerable walls such as basements. It can be used internally and on window reveals to prevent cold bridging.
Suppliers
Thermablok - select ‘Products’ for Aerogel Insulation
Suppliers
Ecological Building Systems - search ‘Calsitherm’
5.6.3 Cavity/hollow wall insulation
In uninsulated homes, around 33% of all heat lost is through the walls. Some older buildings (early to mid 1920s) have a cavity
wall. Filling the cavity with insulation is one way of reducing heat loss. It can also help reduce condensation inside the house which is a common problem in older buildings.
This method is not without risk and if not done correctly can make
damp and condensation problems worse. Walls should be free from damp and defects which could allow moisture penetration. This method should not be used on walls exposed to driving rain.
Additional information should be sought if considering insulating
timber or early masonry cavity walls.
There are opportunities to insulate within hollow wall construction. This building technique is quite common in Cornwall and is often
seen in slate hanging and render on lath and timber framed buildings. Please bear in mind that technical considerations differ
with cavity and hollow wall construction.
54
Sheep’s wool fixed between a timber frame before rendering
Image English Heritage.
THI funded works to traditional slate hung property, Helston.
Traditional laths on timber studwork exposed prior to rendering at Church Street, Helston.
5. Building fabric improvements
Traditional timber stud with brick infill, Helston. Insulation can be
used between original timbers.
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5. Building fabric improvements
Material Price (£/m2)
(Supply & install)
Thermal Conductivity
(W/mK)
Description Applications Lifespan
(years)
Cellulose 140mm damp spray:
£13.00
270mm blown in:
£15.00
0.035 – 0.040 Made from recycled paper. Fire resistant, non-toxic, low embodied energy. Comes loose in bags so can be fitted into most spaces. Also blown in professionally.
Roof, internal wall, floor (not suitable for cavity wall insulation).
20-30
Sheep’s wool 100mm: £10.10
170mm: £13.42 0.035 – 0.040 Natural fibre from a renewable source (sheep) with low
embodied energy. Comes as a roll. Roof, internal wall, floor.
50 plus
Hemp 50mm: £4.30
75mm: £6.45
100mm: £8.60
0.038 – 0.040 Hemp based insulation with similar properties to Sheep’s wool. Comes as a roll.
Roof, internal wall, floor.
100 plus
Flax £52.00 plus depending on availability
0.038 – 0.040 Natural fibre from an inexhaustible source (linen). Comes in a roll.
Roof, internal wall, floor.
100 plus
Wood fibre 80mm: £10.15
100mm: £13.00 0.038 – 0.050 Made from natural wood fibre. High density and
breathable. Comes in batts. Roof, internal wall, external wall, floor
50
Clay board £30.00 0.14 These are composite boards made of clay, reed and hessian.
Internal walls and ceilings.
30
Reed board £22.00 0.056 Rigid building board made from natural reeds. Internal walls and ceilings.
50
Clay render £26.50 0.15 Highly breathable low carbon product which can help regulate humidity levels. Used on top of insulation.
Internal walls. 40
Calsitherm
climate board
15mm: £50.50
30mm: £45.25
50mm: £67.60
Mortar: £51.00
0.059 – 0.066 Made from calcium silicate, a micro porous mineral build-ing material with good insulating properties and high ca-pillary action ensuring humidity regulation. Impervious to mould. Can be faced with a lime based plaster for an aesthetic and breathable surface finish. Climate Board is non-flammable and is classed as A1.
Internal walls. 100 plus
Hemp plaster £96.75 0.05 to 0.09 Made from hemp, lime and recycled minerals, Hempsulate is a low carbon alternative to gypsum based plasters and renders with good breathability and insulating properties.
Internal walls. 75
Cork board £48.35 0.042 vapour permeable board made entirely from natural and renewable cork.
Internal walls. Also can be used internally.
60 plus
5.7 Insulation materials
55 Main contents
5. Building fabric improvements
Material Price (£ / m2)
(Supply & install)
Thermal
Conductivity
(W / mK)
Description Applications Lifespan
(Years)
Secil ecoCORK £110.00 0.18 Natural hydraulic lime insulating render. Internal/external. 100 plus
Limecrete £120.00 0.06 Limecrete is a vapour permeable solid floor which provides an alternative to a concrete floor with or without a DPC.
Floors. 60
Limecrete with insulated clay aggregate
£165.00 0.10 As above but with additional thermal proper-ties.
Floor. 60
Technopor £135 / m³ 0.085 Glass foam granulate. Floor slabs. 70
Hemp-Lime Composite 20mm: £9.90 0.070 – 0.090 Made from hemp and lime. Can be applied like render. Many layers used to increase U value.
External wall. 100
Hempcrete £102.00 0.06 A mixture of hemp shiv and lime with insulating properties. A low carbon alternative to block-work on extensions to historic buildings.
External walls. 100 plus
Hofatex board (Warmshield) £26.00 0.046 Softwood fibre board. External walling. 100 plus
Diffutherm £110.00 0.044 Rigid, hygroscopic insulation board made from natural wood fibres which gives good thermal and acoustic properties.
External walling. 100 plus
Thermaslim aerogel
magnesium silicate board
£15.00-£31.00 0.029 - 0.080 30 Thin fully breathable, rigid hydroscopic insula-tion board available in multiple thicknesses for
increased R values
Internal-useful for window reveals and ceilings
Celotex
(for comparison)
25mm:£6.50
50mm:£11.50
75mm:£15.50
100mm:£17.00
0.021-0.022 50 plus Rigid Polyisocyanurate (PIR) insulation boards Floor/wall (internal and external)/roof
5.7 Insulation materials
56
Unsuitable products:
Mineral wool: all mineral wool has a higher embodied energy and cannot be recycled.
Polystyrene: a synthetic thermoplastic material made by polymerizing styrene, available in solid form or foam, slow to biodegrade
Polyisocyanurate/Polyurethane foam - plastic based product, previously made with CFCs, now produced with hydrofluorocarbons.
Multi-layered foil insulation - thin, easy to handle and safe to cut but not breathable and unsuitable for old buildings.
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5.8 Insulating historic buildings guidance
Historic England
Historic England - Energy efficiency and Historic Buildings External wall insulation in traditional buildings
Insulating older homes [Link no longer available]Insulating pitched roofs at ceiling level - cold roofs
Insulating pitched roofs at rafter level - warm roofs
Insulating flat roofs
Insulating thatched roofs
Insulating dormer windows
Insulation of suspended timber floors
Insulating solid ground floors
Insulating solid walls
Insulating timber framed walls
Early cavity walls
Historic Scotland
Evaluating energy modelling for traditionally constructed dwellings
Fabric Improvements For Energy Efficiency In Historic Buildings
Monitoring thermal upgrades to ten traditional properties
Fabric Improvements for Energy Efficiency in Historic Buildings
Internal wall insulation to six tenement flats
Sustainable Traditional Buildings Alliance (STBA)
STBA Guidance including Planning Responsible Retrofit of Tradition-
al Buildings and The Responsible Retrofit Guidance Wheel.
5. Building fabric improvements
57 Main contents
5.9 Further technical guidance
Buildingconservation.com
Subject Index on Building Conservation
Ten ways to ruin an old building
Local Authority guidance A Bristolian’s guide to solid wall insulation
Cornwall Council - Cornwall Design Guide
Westminster City Council - Retrofitting Historic Buildings
Other organisations
Edinburgh World Heritage - Energy Efficiency in Historic Buildings
Historic Towns Forum - Saving Energy - guide for historic homes
Energy Saving Trust - Roof and Loft Insulation
Bath Preservation Trust - Warmer Bath - energy efficiency guide
SPAB - Information on energy efficiency
BSI Standards - BS 7913:2013 - conservation of historic buildings
Changeworks - Improving energy efficiency in historic buildings
5. Building fabric improvements
58
Converted property near St Keverne with internal walls finished with clay plaster. Works and photo by Clayworks.
Design: Matt Robinson Architecture.
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5.10 Sustainable building products suppliers
Back to Earth - Devon based supplier of natural products
Black Mountain – manufacturer of sheep’s wool and hemp insulation
Cellecta - thermal insulation products
Chroda Eco - ThermoPor, insulating render made from recycled glass
Cornish Lime Company
Ecological Building Systems – sustainable building incl. Calsitherm
Ecomerchant - sustainable building materials supplier
Green Building Store - sustainable building supplier
Isolina – manufacturer of flax insulation
Mike Wye and Associates Ltd - supplier of natural building products
Minster - insulation supplier
NaturePro – sheep’s wool, hemp and wood fibre insulation
NBT – manufacturer of wood fibre insulation including Pavaflex
Tinhay Building Supplies - EcoFill Insulation
Tŷ-Mawr Lime Ltd - Wales based supplier of ecological building
products Womersleys - Eco-friendly materials and building products
Firms specialising in timber repairs
Ventrolla - sash window renovation and draught proofing specialists
Repair Care
Further information on products and services suitable for use
on historic buildings can be found in:
Buildingconservation.com - Building Conservation Directory
6. Sustainable materials
59 Main contents
6. Sustainable materials
6.2 Building materials Always try and use sustainable materials. Natural materials generally have a lower embodied energy and environmental
cost than synthetic materials. Sustainable materials such as Hempcrete, straw bales and cob/rammed earth could provide a
sustainable alternative to conventional concrete blockwork
construction.
Natural ’breathable’ products are always preferable on solid
walled buildings and often prevent deterioration of original fabric. It is advisable to avoid anything oil or cement based, as
these often bind to surfaces in an irreversible manner. This section highlights sustainable products that could be considered when repairing, altering and extending historic buildings. These
products could also be used on new buildings in historic areas.
6.1 Sustainability Sustainable construction is a balance between environmental, social and economic requirements. This guide shows how the envi-
ronmental impacts of energy inefficiency can be resolved through reduced use of fossil fuels (in the context of materials used).
Further information
Cornwall Council - Sustainable Building Guide
Cornwall Council - Sustainable Development
Cornwall Sustainable Buildings Trust
Greenspec homepage
STBA- includes Responsible Retrofit Guidance Wheel tool
Bath/NE Somerset Council - Sustainable Construction & Retrofitting
Bath/NE Somerset Council - Energy Efficiency & Renewable Energy
Deteriorating stonework at All Saints Church, Roskear. Inappropriate hard cement pointing restricts that breathability of
an external wall. Moisture cannot return through the mortar joint and consequently stonework delaminates.
60 Main contents
6. Sustainable materials
6.2.1 Timber Timber should ideally be produced from sustainable sources. Generally this will mean that the impact of logging has been
minimised and a replanting programme is replacing harvested wood. There are certification schemes acknowledged by the
Building Research Establishment (BRE) as acceptable proof of sustainability. Some examples are:
FSC Forestry Stewardship Council
PEFC Program for the Endorsement of Forest Certification
MTCC Malaysian Timber Certification Council
CSA Canadian Standards Association
SFI Sustainable Forest Initiative
The Forest Stewardship Council (FSC) standard is widely accepted
as the most rigorous of these schemes and the only one that is independent of the forestry industry. If in doubt, check against
the relevant certification scheme’s website
Local FSC products and suppliers can be found through:
FSC - UK Product and Supplier Database
Guidance on sourcing suitable sustainable timber:
Greenspec - search ‘timber preservation’
Wood Window Alliance - Specifiers’ Guide to Timber
Windows
Further information on timbers suitable for traditional
building repairs
TRADA - Timber Research and Development Association
IHBC Technical Publications - technical bibliography on timber
SPAB - technical Q and As including timber repair
Reclaimed wood is often preferable for timber repairs as it is
often high quality, has similar properties to existing timber and lasts longer. Although each case should be judged on its own
merits, timber boarding can often be a suitable external cladding
material on new buildings and extensions to historic buildings.
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New buildings with cedar cladding built as part of THI funded conversion of former forge buildings, Trevu Road, Camborne.
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6. Sustainable materials
6.2.2 Hempcrete
Hempcrete is a breathable, highly insulated material made of hemp shiv and lime. It can be used as external walling, timber
frame infill insulation and with the addition of aggregate, floor slabs. Hempcrete regulates the temperature and humidity of a
building; in some cases completely eliminating the need for heating and cooling systems. Hemp can also be grown locally.
Guidance / suppliers
Greenspec - search ‘natural building materials’
The Limecrete Company Ltd - select ‘Hempcrete’
6.2.3 Straw bale construction
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Hemp mortar within timber frame construction.
Straw bale construction is a building method that uses bales of
straw (commonly wheat, rice, rye and oats straw) as structural elements, building insulation, or both. This construction method
is commonly used in natural building or "brown" construction projects.
Advantages of straw bale construction over conventional building systems include the renewable nature of straw, cost, easy
availability, naturally fire-retardant and high insulation value. Disadvantages include susceptibility to rot and high space
requirements for the straw itself. Straw for the bales can be grown locally.
Guidance / case studies
BRE - Straw Bale
Straw bale house, Cornwall
Straw bale house, St Martin. Design: Matt Robinson Architecture.
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Hempcrete house, Roseland near Truro.
6. Sustainable materials 6.2.4 Cob
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Reconstruction of Malthouse Barn, Manaccan, 2005. Works and
photo by Clayworks. Design: Matt Robinson Architecture.
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Guidance / suppliers
Devon Earth Building
Greenspec - search ‘unfired clay bricks’
Muddy Mortars
Cob in Cornwall
Leslie Cornell Building Restoration
Cob is a traditional Cornish building material made of sand, straw and clay sub-soil, mixed with water to produce a moist,
homogenous and malleable material with outstanding thermal capabilities. Originally trampled down by horses, it is now mixed by foot on a tarp, or a JCB for larger quantities. Walls are normally
450-600mm thick, built of masonry plinths in successive layers 600mm high.
When fully dried it becomes very hard, lasting for hundreds of
years as long as it has a solid stone foundation and a good roof.
Unfired clay blocks and bricks are readily available and can also
be used to rebuild earth buildings and in new buildings. Cob bricks were used in a self build house in Gweek (top right image).
Self-build cob house, Gweek. Design: Matt Robinson Architecture.
Cob bus shelter at Helston built with Helston Community College students as part of THI funded live skills training project.
6. Sustainable materials
6.2.5 Thermoplan clay block system
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All photos courtesy of Mike Wye and Associates.
The Thermoplan clay block system is a simple, quick and
sustainable form of construction. Solid honey comb clay building blocks are breathable and have excellent thermal insulation
values requiring no additional insulation.
Guidance / suppliers
Greenspec - search ‘Ziegelwerk Thermoplan ziegel blocks’
The Passivhaus Store - search ‘Thermoplan’
6. Sustainable materials
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6.2.7 Green roofs
Green or sedum roofs can be used on flat or shallow pitched roofs
and can provide environmental benefits. They can provide a habitat for wildlife, temporarily store water during heavy rain,
protect the roof covering from the sun, provide good thermal and acoustic insulation and improve local air quality.
Guidance
Cornwall Council Sustainable Building Guide
Greenspec - search ‘green roofs and planting’
Livingroofs.org - green and living roofs in the UK
Green roof on Lakeside Café, Helston.
6.2.6 Rammed earth
Rammed earth walls are constructed by compacting (ramming) moistened subsoil between temporary formwork panels. When
dried, the result is a dense, hard monolithic wall.
Rammed earth is an ancient form of construction, usually associated with arid areas. Many examples worldwide prove that rammed earth is a successful and durable way of building. A few
historical rammed earth buildings are to be found in the UK.
In recent years, rammed earth has become popular amongst environmentally conscious architects. The Visitor Centre at the
Eden Project near St Austell is constructed of rammed earth.
Guidance
Greenspec - search ‘Rammed Earth’
University of Bath - Developing Rammed Earth for UK Housing
Earth Building UKI
Visitor centre at Eden Project, St Austell.
Sedum roof on barn conversions, Mawnan Smith.
6. Sustainable materials
6.2.8 Sustainable finishes
Volatile Organic Compounds (VOCs) are chemicals that can evapo-
rate into the air usually at room temperature and often produce an odour. VOCs can be harmful to the environment and human health
and are often found in conventional paints.
Sustainable and breathable paints are now available which could
provide health benefits to occupants when used internally:
Lime paint
A breathable paint highly suited to lime rendered buildings that can be used both internally and externally.
Limewash A traditional finish to solid walls which when applied to a porous
wall soaks in, absorbs carbon dioxide and reverts back to lime-stone. It can be used on internal and external surfaces and can be
coloured using pigments.
Clay paint A green, sustainable and vapour permeable alternative to emulsion paints. It helps to control internal humidity and condensation but
should not be used on damp walls.
Linseed paint - Environmentally friendly, long-lasting and cost effective paint, made from natural 100% pure linseed oil. It can
last up to 15 years (up to 3 times longer than modern paints).
Naturepaint
A breathable powder paint made using locally sourced clay.
Mineral silicate paint A strong, stable and breathable paint, very durable and long
lasting with a good colour range.
General guidance
Buildingconservation.com - articles on paint / decorative finishes
Historic England - I Want To Redecorate My House
Cornish Lime Company
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Huers Hut, Towan Head, Newquay. Lime painted, bag rubbed external rubble wall.
THI funded traditional window reinstatement painted internally with linseed paint at the orangery, Rosewarne House, Camborne.
Process Costs
(Supply & install
rates) per m²
Lifespan in years
(based on regular
maintenance)
Lime paint £12.00 7
Limewash £5.25 5-7
Clay paint £4.85 5-7
Linseed paint £8.60 15-20
Breathable (microporous) paints
£14.00 20
Mineral silicate paint £7.95 5-7
Conventional paint (low / standard)
£4.95 3-10
Conventional paint (high quality)
£7.80 5-15
Oil based gloss paints £7.80 15-20
Water-borne gloss paints
£5.15 10-15
Wood stains £10.50-42.00 10-15
Varnishes £6.20 10-15
Timber oils £5.30 15-20
Lead paints (specialist uses only)
£21.00 20-30
Linseed oil / synthetic alkyd resin paint (lead alternative)
£8.30 15-20
6. Sustainable materials
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6.2.9 Painting traditional joinery
Good preparation and appropriate primers, undercoats, paints
and stains will extend the period needed to repaint traditional windows and doors and avoid the need for replacement. Paints
are available now with long lifespans benefiting retention of original fabric. Suitable paints for traditional joinery include:
Oil based gloss paints
Consisting of a primer, undercoat and gloss top coat.
Water-borne gloss paints More flexibility over time and do not yellow.
Wood stains Oil based or water borne and semi transparent or opaque. Some stains are ‘Microporous’ meaning vapour passes through them
without breaking the skin which can allow an unseasoned wood to dry out more easily.
Varnishes
Oil or water based generally labelled as ‘Yaught’, ‘Spar’ or ‘Front Door’. Usually will not last as long outside as paint needing more
maintenance).
Timber oils Usually used on naturally oily woods such as teak. Needs to be
applied to bare wood, hard to maintain in exposed locations and are slightly soft retaining dirt.
Lead paints
Durable paint can be used on Grade 1 and 2* listed build-ings. Originally contained harmful white lead which since 1960’s has been replaced with other less harmful pigments).
Lead paint is restricted by environmental law due to its toxicity. Its use is permitted under license for use on Scheduled Ancient Monuments, Grade I and II* listed buildings, and artworks.
Historic England - Sourcing Lead Paint provides information on
permitted uses and licensing requirements.
6. Sustainable materials
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Natural breathable paints
Auro - natural eco paints, wood stains, floor oils and finishes
Nutshell Paints - natural paints, wood treatments,
varnishes, stains
The Organic and Natural Paint Co.
Earth Born Paints - natural ‘breathable’ water based paints
Primers
Auro - primers for wood and metal
Cornish Lime company - range of primers
6.2.10 Finishes-Suppliers
Clay paints
Clayworks - clay plaster and clay wall systems
Mike Wye and Associates — search ‘Kreidezeit Vega’ (interior)
High performance paints
Zinsser - search ‘Grade 1’ - zero tension paint (interior use)
Lead alternative paint
Technical Paint Services - search ‘lead free paints’
Limewash
Cornish Lime Company - search ‘limewash’
Little Greene - select ‘limewash’
Lime paints
Cornish Lime Company - search ‘lime paint’
Linseed paints
Linseed Paint Company
Old House Store - search ‘Allback linseed oil paint’
Oricalcum
Microporous paint
Sadolin - search ‘Woodshield’ - a flexible paint for wood
Mineral paints
Beeck - Mineral Silicate Paints
Earthborn—Ecopro silicate masonry system
Tŷ-Mawr - search ‘paint’ to view a range of mineral paints
Mike Wye and Associates - search ‘Kreidezeit GekkkoSOL paint’ Amel Linseed oil/synthetic alkyd resin paint used on THI funded
joinery repairs at Rosewarne House, Camborne.
Reconstruction of cob/stone built Malthouse Barn, Manaccan, 2005. Works by Clayworks. Design: Matt Robinson Architecture.
6. Sustainable materials
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Process Costs per m²
(Supply & install rates)
Lifespan in years
(based on regular maintenance)
Hempcrete £102.00 100 plus
Straw bale £130.00 100
Cob £151.00 100
Rammed earth £215.00 100 plus
Clay renders (internally and externally
£26.00 40
Cedar Cladding £150.00 50-100
Standard concrete block £47.00 100
Rendered cavity blockwork wall £73.00-£94.00 60 (render)
Thermoplan clay block £85.00-£105.00 100
Green/Sedum Roof Intensive - high maintenance (shrubs, trees, lawn)
£125.00-£155.00 30-50
Green/Sedum Roof Extensive - low maintenance (e.g. mosses, herbs)
£12.50-£15.60 30 -50
Flat felt roof £101.00-£125.00 15
6.2.11 Sustainable building materials
New cob bus shelter, Water-Ma-Trout, Helston. Works funded by Helston THI.
Further guidance
AECB - The Sustainable Building Association
The Alliance for Sustainable Building Products
Cornwall Sustainable Buildings Trust
Devon Earth Building Association
Greenspec - green building products / design / materials
UK Green Building Council
7. Reclaimed and recyclable materials
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7. Reclaimed and recyclable materials
7.1 Architectural salvage
Care is needed when using reclaimed materials in case they have been taken from other historic buildings or have a short lifespan.
There are many occasions, however, when they are acceptable. Reclaimed wood for scarfing repairs to original windows, for example, has similar properties to the wood of the original
windows and provides long term benefits. Old wood was often heartwood and will last longer than newer wood. Architectural
salvage companies can be a good source for reclaimed products.
Further information / suppliers
Salvoweb - directory of architectural salvage and antiques.
Eden Reclamation - architectural salvage near Eden Project
Shiver Me Timbers Reclamation Yard, Crowlas, nr Penzance
Stax Reclamation - Saltash based architectural salvage
Trenoweth Roofing and Reclamation Services Ltd, Penzance
Truro Reclamation, Newquay
7.3 Metal rainwater goods
Traditional leading and rainwater goods add significantly to the
character of a historic building. Cast iron or aluminium rainwater goods are a sustainable option which can be made from recycled
materials. Cast iron rainwater goods for example can include up to 70-75% of recycled content and can last over 60 years. Aluminium can contain up to 33% of recycled content and can
last up to 60 years. This contrasts with plastic alternatives which are harmful to produce and last less than half as long.
Guidance / suppliers
The Building Conservation Directory A guide to specialist suppliers, consultants and craftsmen
Greenspec - search ‘rainwater goods pipes and fittings’
Alumasc rainwater systems
Tuscan Foundry - Devon based cast iron guttering, radiators etc
Guidance on maintenance of rainwater goods
SPAB National Maintenance Week
Buildingconservation.com - maintaining / preserving cast iron rainwater systems
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7.2 Minimising waste Minimising waste during building works will reduce the amount of material to be disposed of at landfill. This has associated financial
and environmental benefits.
Cornwall Council - Recycling, rubbish and waste
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8. Funding options
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8. Funding options 8.1 Current funding schemes
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Energy Companies Obligation (ECO)
The ECO is a government scheme requiring energy companies to support vulnerable people and those on lower incomes. One of the
targets set by the ECO is Affordable Warmth which gives assistance to homeowners or tenants on certain benefits to heat
their homes affordably. This is through:
Cold Weather Payment
If you are on benefits and your local temperature is either recorded as, or forecast to be, an average of zero degrees Celsius
or below over 7 consecutive days you may be entitled to a Cold
Weather payment.
Warm Home Discount Scheme
You may be entitled to a one off discount on your electricity bill if
you receive the Guarantee Credit element of Pension Credit (even if you get Savings Credit as well), your name is on the bill and
your electricity supplier is part of the scheme.
Winter Fuel Payment
You may be entitled to a tax free payment to help pay your
heating bills if you were born on or before 5 January 1953.
Further information:
Details of all of these schemes are available from the Gov.uk web
page:
‘Help from your energy supplier:the Affordable Warmth Obligation’
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Domestic Renewable Heat Incentive (RHI)
Funding could be available for renewable heating costs for
biomass boilers, solar water heating and certain heat pumps. Payments are made for 7 years and are based on the amount
of renewable heat made by your system.
Further information:
Domestic Renewable Heat Incentive (RHI)
Other external links
Department of Energy & Climate Change
Energy Saving Trust
Community Energy Plus
Feed-in Tariff (FIT)
Payments from your energy supplier are possible if you generate
your own electricity through renewable heat such as solar panels or wind turbines.
This is through generation tariffs where a set amount is given for each unit (kilowatt hour or KWh) and an export tariff where any
extra units not used can be sold back to your supplier.
Further information:
Feed-in Tariffs: get money for generating your own electricity
8. Funding options
8.2 Tax savings
Landlords Energy Saving Allowance (LESA)
Landlords who improve the energy efficiency of their properties are entitled to a £1500 allowance per property.
See website for further details:
Gov.uk - Landlords Energy Saving Allowance
Enhanced Capital Allowances (ECA)
Tax breaks are also available under the Enhanced Capital Allowances scheme, offering 100% first-year capital allowances on investments in ‘green plant and machinery’, such as energy
saving industrial and office equipment. In practice the ECA would also entitle a landlord to claim 100% tax on a new boiler.
See website for details:
The Enhanced Capital Allowance Scheme
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Cornwall Council’s grants advice service
Cornwall Council provides a grants advice service with current information on available grants, primarily for community or
business groups. Some of these may be relevant to owners of historic buildings:
Cornwall Council - grants advice service
9. Further information and advice
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9. Further information and advice
Cornwall Council Planning and Historic Environment
Tel: 0300 1234 151 planning@cornwall.gov.uk
Community Energy Plus
www.cep.org.uk
Community Energy Plus is a charity and social enterprise providing a range of services to help householders, communities and businesses reduce their energy use and create a more sustainable
future for all in Cornwall. For the last fifteen years they have worked in partnership with a number of public, private,
charitable and voluntary organisations to support innovative projects relating to energy efficiency and renewable energy.
Telephone: 0800 954 1956 Email: advice@cep.org.uk
Cornwall Sustainable Building Trust
www.csbt.org.uk
CSBT is a charitable company committed to making building design and construction as sustainable as possible, with minimal negative impact on the environment, both locally and globally.
CSBT OBJECTIVES:
To raise awareness and minimise the effects of construction on
the Cornish and global environments.
To promote sustainable construction by demonstration tolocal communities and the construction sector that it can make economic sense.
To preserve, protect and enhance the environment of Cornwall.
To act as a single source of expert advice for Local and
Strategic Planning Authorities and others.
Historic England
www.historicengland.org.uk
Historic England is a public body that looks after England’s historic environment. It champions historic places, helping
people understand, value and care for them. It advises on planning and conservation issues, and provides support through
grants and other resources. It offers:
Advice on management and enhancement of the historic
environment based on published conservation principles andpromotes managing change through ‘constructive
conservation’.
Holds many information databases and produces a widevariety of publications which can be downloaded online for
free, including energy conservation in historic buildings.
Historic England’s South West Office covers Cornwall
Heritage and Climate Change - Historic England guidance on climate change and saving energy in older buildings
Carbon Trust
www.carbontrust.co.uk
The Carbon Trust’s mission is to accelerate the move to a low carbon economy by working with organisations to reduce carbon emissions and develop commercial low carbon technologies.
It provides a range of products and services to businesses, including online resources and publications.
Energy Saving Trust
energysavingtrust.org.uk
The Energy Saving Trust is organised as a social enterprise organisation with charitable status. Their website is full of useful
information and advice and they operate a free advice phone
line on 0300 123 1234.
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9.1 Organisations
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9. Further information and advice
Cornwall Council
Historic Environment Advice: 0300 1234 151
Building Control: 0300 1234 151
buildingcontrol@cornwall.gov.uk
Planning Advice: 0300 1234 151
planning@cornwall.gov.uk
Sustainable Development
http://www.cornwall.gov.uk/default.aspx?page=2972
Conservation advice
The Heritage Help website includes advice on protection and
planning, caring and conserving and heritage organisations:
http://heritagehelp.org.uk/
9.2 Professional services It is important to use suitably qualified and competent contractors and professionals when undertaking works to
historic buildings. Lists of conservation accredited professionals are available from the following links:
Royal Institute of British Architects (RIBA): http://www.architecture.com/Explore/Home.aspx
Royal Institute of Chartered Surveyors (RICS): https://www.ricsfirms.com/
Conservation accredited structural engineers:
https://www.istructe.org/about-us/how-we-are-structured/associated-organisations/
Institute of Historic Building Conservation:
http://www.ihbc.org.uk/
IHBC Yearbook
Federation of Master Builders:
http://www.fmb.org.uk/
The Building Conservation Directory
https://www.buildingconservation.com/
Further information / guidance
Historic England
Heritage and Climate Change
Historic Environment Local Management:
www.helm.org.uk
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AECB - The Sustainable Building Association
The Association of Environmentally Conscious Builders (AECB) is a network of individuals and companies with a common aim of
promoting sustainable building.
http://www.aecb.net/
The Society for the Protection of Ancient Buildings (SPAB)
SPAB provides advice on historic building repairs over the telephone, has a range of technical publications and runs regular
courses and events.
https://www.spab.org.uk/ Telephone: 020 7377 1644
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9. Further information and advice
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9.3 Local contractors for historic
building work
A list of contractors who have carried out traditional repairs
as part of THI and HERs schemes in Cornwall can be obtained from: andrew.richards@cornwall.gov.uk
Sw-ecohub
This is a social enterprise website owned and run by Cornwall Sustainable Building Trust (CSBT) giving information on
environmentally sensitive building methods, locally available eco supplies, alternative products/services and consultants.
Institute of Conservation (ICON)
Conservation register for finding professionally qualified conservator-restorers in the UK/Ireland
Local contractors with experience in historic and
sustainable construction:
Cathedral Builders
Clayworks
Darrock and Brown
Jack in the Green - Traditional and conservation builders
JJ Sharpe
Mike Wye and Associates Ltd
Muddy Mortars
Ventrolla
We are aware of the work of the contractors above in historic building renovation. Other suitable contractors may be available.
Limecrete slabs being laid. Photo courtesy of Matthew
Clements / Mike Wye and Associates Ltd.
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